Plate Creation Research Articles

Reverse-faulting earthquakes and the tectonics of slowly-spreading mid-ocean ridge axes

We examine the distribution and characteristics of 70 reverse-faulting earthquakes at slowly-spreading ridges in the Atlantic and Indian Oceans. All were large enough (Mw≥4.7) for their focal mechanisms to be determined and listed in the gCMT catalogue (www.globalcmt.org/). Of these, 21 were sufficiently large (Mw≥5.3) for detailed body-waveform analysis to determine accurate mechanisms, centroid depths and water depths at their epicentres. All had shallow centroids 1–3 km below the sea bed, and occurred beneath gravity and bathymetric highs on ridge flanks, not in the axial valley, consistent with the locations of reverse-faulting microearthquakes discovered in earlier OBS experiments. We describe a simple quantitative model that explains their occurrence by the bending of an elastic layer about 3 km thick as it is uplifted and exhumed into the dome of a core complex by detachment faulting. The widespread distribution of such events, and their global seismic moment-release rate, suggests that asymmetric spreading in core complexes is the dominant mode of extension at such slowly-spreading ridges. Such an inherently asymmetric process is capable of producing a steady-state axial rift valley, and the overall symmetry of plate creation, but only if its polarity reverses in space and time along the axis of the ridge, for which there is some evidence in the gravity from altimetry.

Robot-Assisted Radical Cystectomy with Modified Vesica Ileale Padovana (VIP) Neobladder Configuration Using a Hybrid Approach: Initial Experience.

We developed a new technique to fold a neobladder (NB) simply by using a modified Vesica Ileale Padovana (VIP) with a hybrid approach. We provide a step-by-step description of our technique as it was used in this initial experience. A total of 10 male patients with a median age of 66 years underwent robot-assisted radical cystectomy (RARC) with an orthotopic NB via a hybrid approach from March 2022 to February 2023. After the isolation of the bladder and bilateral pelvic lymphadenectomy, Wallace plate creation was performed, and the robot was undocked. We extracorporeally performed the removal of the specimen and a side-to-side ileoileal anastomosis, and then the VIP NB posterior plate was rotated 90 degrees counterclockwise using a 45 cm detubularized ileum. The robot was redocked; then, circumferential urethra-ileal anastomosis, side-to-middle anterior wall closure, and ureteric afferent limb anastomosis were performed. The median estimated blood loss was 524 mL, and the mean operative time was 496 min. Patients had a high continence rate, and no high-grade complications were observed. The NB configuration using the modified VIP method for a hybrid approach is a feasible surgical technique to minimize the movement of robotic forceps. In particular, it may be more useful in Asian individuals with narrow pelvises.

A fresh "slant" on modified Mitchell bladder neck reconstruction: A contemporary single-institution experience.

IntroductionPatients with neurogenic urinary incontinence due to an incompetent outlet may be offered bladder neck reconstruction, but the quest for the perfect surgical-outlet procedure continues. Our aim was to characterize continence and complications after modified Mitchell urethral lengthening/bladder neck reconstruction (MMBNR) with sling and to introduce a modification of exposure that facilitates subsequent steps of MMBNR.MethodsA single-institution, retrospective cohort study of patients who underwent primary MMBNR between May 2011 and July 2019 was performed. Data on demographics, urodynamic testing, operative details, unanticipated events, continence, bladder changes, and additional procedures were collected. A 2013 modification that permits identification of the incompetent bladder neck prior to urethral unroofing was applied to the last 17 patients. The trigone and bladder neck are exposed via an oblique low anterolateral incision on the bladder. Ureteral reimplantation is not routinely performed. Focal incision of the endopelvic fascia after posterior plate creation limits breadth of blunt dissection for sling placement. Descriptive statistics were utilized.ResultsA total of 25 patients (13 females) had MMBNR with sling at a median age of 10 years [interquartile range (IQR) 8–11]. Bladder augmentation was performed concurrently in 14/25 (56%) patients. At a median of 5.0 (IQR 3.9–7.5) years follow-up after MMBNR, 9/11 (82%) without bladder augmentation and 13/14 (93%) with bladder augmentation had no leakage per urethra during the day without further continence procedures. Of the three patients with persistent incontinence, two achieved continence with bladder wall Botox injection (overall continence 24/25, 96%). New and recurrent vesicoureteral reflux was noted in five patients and one patient, respectively. Two patients required subsequent bladder augmentation for pressures and one other will likely require it. None have required bladder neck closure or revision.ConclusionMMBNR with sling provides promising continence per urethra in neurogenic bladder with low need for secondary continence procedures. Ongoing modifications may achieve elusive total continence.

Expert system for the production of personalized cloverleaf plate implant for human humerus

The Expert framework for the Development of Customized Cloverleaf Plate, model is developed and introduced in this paper for the purpose of proper plate selection, and description the geometry and morphology. The Expert System consists of a User Defined Function (UDF) for the development of a customized geometric plate model and a small-scale Expert System for the selection of the correct production method. UDF depends on the model of parametric developed, of the plate implant, which is updated in this research. Expert system is a system which is currently based on the expert knowledge, but additional improvement is scheduled for the following period, e.g. machine learning application. The Expert Framework will give great benefits for the doctors and engineers because it will enable proper pre-operative planning, production of plate implants, end education of medical practitioners and students. By the authors opinion, the most important benefit is the established modular system for the plate creation, which means that any additional knowledge for the plate creation and application can be added and used into The Expert Framework.

V09-11 WATCH SHAPED BUCCAL MUCOSA GRAFT FOR SIMULTANEOUS CORRECTION OF SEVERE CHORDEE AND URETHROPLASTY AS A ONE STAGE REPAIR OF SCROTAL HYPOSPADIAS

You have accessJournal of UrologyPediatrics (V09)1 Apr 2020V09-11 WATCH SHAPED BUCCAL MUCOSA GRAFT FOR SIMULTANEOUS CORRECTION OF SEVERE CHORDEE AND URETHROPLASTY AS A ONE STAGE REPAIR OF SCROTAL HYPOSPADIAS Miroslav Djordjevic*, Abdulmuttalip Simsek, Marta Bizic, Borko Stojanovic, Joshua Roth, and Rajveer Purohit Miroslav Djordjevic*Miroslav Djordjevic* More articles by this author , Abdulmuttalip SimsekAbdulmuttalip Simsek More articles by this author , Marta BizicMarta Bizic More articles by this author , Borko StojanovicBorko Stojanovic More articles by this author , Joshua RothJoshua Roth More articles by this author , and Rajveer PurohitRajveer Purohit More articles by this author View All Author Informationhttps://doi.org/10.1097/JU.0000000000000923.011AboutPDF ToolsAdd to favoritesDownload CitationsTrack CitationsPermissionsReprints ShareFacebookLinked InTwitterEmail Abstract INTRODUCTION AND OBJECTIVE: Severe hypospadias repair still presents a great challenge. We evaluated a novel approach of using a specially shaped buccal mucosa graft for simultaneous ventral tunica grafting and new urethral plate creation in combination with a longitudinal dorsal island skin flap for a one-stage repair of severe hypospadias. METHODS: A 14-month-old boy underwent scrotal hypospadias repair. The short and non-elastic urethral plate is divided. Buccal mucosa graft is harvested from the inner cheek, and designed in a special “watch” shape, with the spherical part in the middle and two rectangular parts on both sides. The tunica albuginea is opened ventrally for penile straightening and grafted to the spherical part of the "watch-shaped" buccal mucosa with 6-8 “U-shape” stitches. The rectangular parts are fixed to the tip of the glans distally and native urethral meatus proximally. A longitudinal dorsal skin flap is harvested, button-holed ventrally and joined with the buccal graft. Penile skin reconstruction is performed using available penile skin. RESULTS: Good appearance of the penis is achieved without residual chordee, urethral fistula or stricture. CONCLUSIONS: A watch shaped buccal mucosa graft for simultaneous curvature correction and urethroplasty could be a good choice for single stage repair of scrotal hypospadias with severe chordee. Source of Funding: None © 2020 by American Urological Association Education and Research, Inc.FiguresReferencesRelatedDetails Volume 203Issue Supplement 4April 2020Page: e836-e836 Advertisement Copyright & Permissions© 2020 by American Urological Association Education and Research, Inc.MetricsAuthor Information Miroslav Djordjevic* More articles by this author Abdulmuttalip Simsek More articles by this author Marta Bizic More articles by this author Borko Stojanovic More articles by this author Joshua Roth More articles by this author Rajveer Purohit More articles by this author Expand All Advertisement PDF downloadLoading ...

Automated High Throughput Objective Assessment of Human Taste Palatability Predictive of Consumption

Psychoactive drugs are characterized by stimulus properties that generate qualitative interoceptive stimuli, and by reinforcing properties that promote or suppress drug consumption. Similarly, tastant agonists, chemicals that stimulate T1R and T2R receptors expressed in taste buds, also can be thought of as carrying stimulus properties which generate taste qualities, and reinforcing properties that impact tastant consumption. Objective measure of taste quality in both humans and animals is obtained from taste discrimination assays, but objective quantification of “palatability”—the property that determines tastant consumption—only is evident in animal models. We previously reported a high throughput automated system for human taste discrimination, the TaStation®. We have further developed the TaStation® for objective measurements of palatability that predict tastant consumption. The basis of the method is a game in which subjects spend money from a limited virtual “bank account” to create an “ideal plate”—a 96‐well plate that, from the subject's perspective, contains the best‐tasting set of samples. The samples (200 μl each) to be evaluated are randomly presented to subjects in replicates, drawn by an electronic pipette from another 96‐well plate, the “source plate.” Subjects self‐administer each sample from the pipette to the tongue, then select one of two buttons, labelled “Include” or “Exclude,” appearing on a touch‐sensitive display. A button‐touch indicates a subject's intention to include the sample in, or exclude it from, their ideal plate. A subsequent touch on a monetary scale (range = $0.00 to a pre‐set maximum) also appearing on the display indicates the price the subject will pay (withdrawn from their bank account) to actuate the inclusion‐exclusion operation. The amount spent is equated with a probability that the inclusion‐exclusion choice will be carried forward—maximum allowed expenditure buys a probability of 1.0 guaranteeing execution of the subject's choice, whereas a zero expenditure results in a probability of 0.5 that the sample will be either included or excluded. Samples for which a subject spends the highest amounts either predominate (“Include”) or are absent (“Exclude”) in the final ideal plate. Approximately half of the samples for which a subject spends nothing appear in the final ideal plate. After 96 such trials, the completed ideal plate is submitted to a computer‐generated virtual market that rewards the subject for their ideal plate creation efforts by returning a monetary value on the plate content. At the game's conclusion, the subject is remunerated in actual money for the amount remaining in their bank account and for the amount returned by the virtual market. The rewards are balanced to ensure incentive for spending the limited bank account resources toward ideal plate design. A subject's taste “preferences” can readily be discerned from the final ideal plate configuration, and the amounts spent for each tastant operationally quantifies palatability. In a series of tests, the amounts spent per sample closely mirrored actual volumes consumed by each subject measured from 30 ml samples of the same tastant solutions, thereby providing a validation of the TaStation® method for objective quantification of palatability.Support or Funding InformationFunded entirely by Opertech BioThis abstract is from the Experimental Biology 2019 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.

Buccal mucosa graft for simultaneous correction of severe chordee and urethroplasty as a one-stage repair of scrotal hypospadias (watch technique).

Severe hypospadias repair still presents a great challenge. We evaluated a novel approach of using a specially shaped buccal mucosa graft for simultaneous ventral tunica grafting and new urethral plate creation, in combination with longitudinal dorsal island skin flap, as a one-stage repair of severe hypospadias. Between July 2014 and September 2017, 26 patients (aged from 12 to 22months) underwent scrotal hypospadias repair. Short and non-elastic urethral plate is divided. Buccal mucosa graft is harvested from the inner cheek, and designed in a special "watch" shape, with the spherical part in the middle and two rectangular parts on both sides. Tunica albuginea is opened ventrally for penile straightening and grafted to the spherical part of the "watch-shaped" buccal mucosa with 6-8 "U-shape" stitches. The rectangular parts are fixed to the tip of the glans distally and native urethral meatus proximally. Longitudinal dorsal skin flap is harvested, button-holed ventrally and joined with buccal graft. Penile skin reconstruction is performed using available penile skin. The mean follow-up was 22months (range from 9 to 46months). Satisfactory results were achieved in 22 patients. Two urethral fistulas were successfully repaired by minor surgery after 3months, while one meatal stenosis and one urethral diverticulum were successfully treated by temporary urethral dilation. There were no cases of residual curvature. Specially shaped buccal mucosa graft for simultaneous curvature correction and urethroplasty could be a good choice for single-stage repair of scrotal hypospadias with severe curvature.

Low-Temperature Alteration of the Seafloor: Impacts on Ocean Chemistry

Over 50% of Earth is covered by oceanic crust, the uppermost portion of which is a high-permeability layer of basaltic lavas through which seawater continuously circulates. Fluid flow is driven by heat lost from the oceanic lithosphere; the global fluid flux is dependent on plate creation rates and the thickness and distribution of overlying sediment, which acts as a low-permeability layer impeding seawater access to the crust. Fluid-rock reactions in the crust, and global chemical fluxes, depend on the average temperature in the aquifer, the fluid flux, and the composition of seawater. The average temperature in the aquifer depends largely on bottom water temperature and, to a lesser extent, on the average seafloor sediment thickness. Feedbacks between off-axis chemical fluxes and their controls may play an important role in modulating ocean chemistry and planetary climate on long timescales, but more work is needed to quantify these feedbacks.

A new animation of subduction zone processes developed for the undergraduate and community college audience

Today’s undergraduate students are accustomed to animations as impor­tant to their learning. Complex geologic processes such as subduction are well suited to animation. In spite of this opportunity and need, high-quality animations of fundamental Earth processes are uncommon. We have produced a realistic animation of plate creation and destruction processes for the undergraduate audience. First steps focused on building a storyboard, which is a visual outline of scenes to be animated. Then we organized a team of geoscientists and animators to make the animation. Students generated a rough draft animation, which was polished by a professional animator. We also wrote a narrative that was keyed to the animation, with written “call outs” inserted when terms that may be unfamiliar to undergraduates were spoken. Concepts in the animation are explicitly linked to the scientific literature, with references intended to guide interested viewers to sources to learn more. After the animation and narration were completed, we focused on dissemination and assessment. The animation (“Plate Tectonics Basics 1”) was placed on YouTube and the Science Education Resource Center (SERC) portal, and a Japanese version was made. Presentations about the animation were given at the Geological Society of America (GSA) annual meeting and the American Geophysical Union (AGU) Fall meeting. Assessment focused on capturing student understandings before and after watching the animation. Three groups of students were assessed: community college students and lower- and upper-level students at a four-year university. Results of the assessment indicate that students at all levels improved their understanding of subduction zone processes after experiencing the animation, but that upper-level students showed the greatest improvement. More high-quality animations about important plate tectonic processes and additional research into the level of complexity for various student groups are required.

A Novel Computer-Aided Approach for Parametric Investigation of Custom Design of Fracture Fixation Plates.

The present study proposes an integrated computer-aided approach combining femur surface modeling, fracture evidence recover plate creation, and plate modification in order to conduct a parametric investigation of the design of custom plate for a specific patient. The study allows for improving the design efficiency of specific plates on the patients' femur parameters and the fracture information. Furthermore, the present approach will lead to exploration of plate modification and optimization. The three-dimensional (3D) surface model of a detailed femur and the corresponding fixation plate were represented with high-level feature parameters, and the shape of the specific plate was recursively modified in order to obtain the optimal plate for a specific patient. The proposed approach was tested and verified on a case study, and it could be helpful for orthopedic surgeons to design and modify the plate in order to fit the specific femur anatomy and the fracture information.

Haptic computer-assisted patient-specific preoperative planning for orthopedic fractures surgery.

The aim of orthopedic trauma surgery is to restore the anatomy and function of displaced bone fragments to support osteosynthesis. For complex cases, including pelvic bone and multi-fragment femoral neck and distal radius fractures, preoperative planning with a CT scan is indicated. The planning consists of (1) fracture reduction-determining the locations and anatomical sites of origin of the fractured bone fragments and (2) fracture fixation-selecting and placing fixation screws and plates. The current bone fragment manipulation, hardware selection, and positioning processes based on 2D slices and a computer mouse are time-consuming and require a technician. We present a novel 3D haptic-based system for patient-specific preoperative planning of orthopedic fracture surgery based on CT scans. The system provides the surgeon with an interactive, intuitive, and comprehensive, planning tool that supports fracture reduction and fixation. Its unique features include: (1) two-hand haptic manipulation of 3D bone fragments and fixation hardware models; (2) 3D stereoscopic visualization and multiple viewing modes; (3) ligaments and pivot motion constraints to facilitate fracture reduction; (4) semiautomatic and automatic fracture reduction modes; and (5) interactive custom fixation plate creation to fit the bone morphology. We evaluate our system with two experimental studies: (1) accuracy and repeatability of manual fracture reduction and (2) accuracy of our automatic virtual bone fracture reduction method. The surgeons achieved a mean accuracy of less than 1mm for the manual reduction and 1.8mm (std [Formula: see text] 1.1mm) for the automatic reduction. 3D haptic-based patient-specific preoperative planning of orthopedic fracture surgery from CT scans is useful and accurate and may have significant advantages for evaluating and planning complex fractures surgery.

MScreen: An Integrated Compound Management and High-Throughput Screening Data Storage and Analysis System

High-throughput screening (HTS) has historically been used by the pharmaceutical industry to rapidly test hundreds of thousands of compounds to identify potential drug candidates. More recently, academic groups have used HTS to identify new chemical probes or small interfering RNA (siRNA) that can serve as experimental tools to examine the biology or physiology of novel proteins, processes, or interactions. HTS presents a significant challenge with the vast and complex nature of data generated. This report describes MScreen, a Web-based, open-source cheminformatics application for chemical library and siRNA plate management, primary HTS and dose-response data handling, structure search, and administrative functions. Each project in MScreen can be secured with passwords or shared in an open-information environment that enables collaborators to easily compare data from many screens, providing a useful means to identify compounds with desired selectivity. Unique features include compound, substance, mixture, and siRNA plate creation and formatting; automated dose-response fitting and quality control (QC); and user, target, and assay method administration. MScreen provides an effective means to facilitate HTS information handling and analysis in the academic setting so that users can efficiently view their screening data and evaluate results for follow-up.

Tectonic sedimentology: sediment systems deciphering global to local tectonics

AbstractTectonic sedimentology has broad appeal because it can be applied at many time and length scales, such as sedimentary consequences of: changing rates of plate creation at mid‐ocean ridges, continent–continent collisions, plateaux uplift, active plate margins, extensional rift tectonics and the birth, growth and death of individual folds and faults. Tectonic sedimentology deals with the direct influence of neotectonics on sedimentation and basin development, and with the inverse problem of reconstructing the order and development of palaeotectonic structures. This review attempts to show how the scope and importance of the subject has developed over the last decade and is divided into five themes: (i) At the largest tectonic scale, constraints on mid‐ocean ridge activity and continent–continent collisions come from: (a) precise chemical analyses of fluid inclusions in marine halite deposits dating back to ca 550 Ma; (b) Sr‐isotopic ratios of marine Phanerozoic calcitic fossils; and (c) chemical composition of Archaean and Proterozoic banded iron formations. (ii) At regional scales, constraints on the timing and extent of continental plateau uplift/incision and cratonic tilting are given by: (a) palaeoaltimetry estimates from oxygen isotope depletion in carbonate palaeosols; (b) radiometric dating of palaeowater‐table speleothems; and (c) preferential river migration. (iii) At basin scales, catchment processes are emphasized as key controls on sediment flux from tectonic uplands to sedimentary basins. The inadequacy of sediment transport algorithms based on tractive stress and flow power to describe erosion, incision and sediment transport during the most formative catchment hydrological events is emphasized. (iv) Rates of basin‐scale fault and fold growth, displacement, death and basement uplift are provided by application of facies analysis and sequence stratigraphy to accurately‐dated sediments in sedimentary basins. (v) The effects of changing climate and varying basin base‐level in modifying tectonic influences on erosion and sedimentation are examined. In such cases, experimental and numerical modelling using multi‐variate parameters of subsidence rate, sediment supply and sea‐level change can shed light on the problem. Future developments will undoubtedly improve such models, hopefully establishing full linkage and feedback between sediment/water supply and changing climate within an overall tectonic framework that may itself be changing.

An Innovative Way to Create Assay Ready Plates for Concentration Response Testing using Acoustic Technology

A totally integrated serial dilution assay plate preparation system that fully uses the high precision nanoliter dispensing capabilities of acoustic liquid handlers has been developed and implemented. The application uses a hybrid of a serial dilution method and a direct dilution method, achieving a wide concentration range for the dilution series, while avoiding additive errors inherent to traditional serial dilution methods. The method allows assay miniaturization, which greatly reduces reagent and consumable costs to the customers. The system is in production at AstraZeneca and has generated high-quality assay ready plates for high-throughput screening and secondary screening since 2005. Further development in recent years has expanded the flexibility of the assay ready plate creation process to meet varied screening requirements. We will discuss the requirements for assay ready plates for concentration response testing and describe the novel plate creation method in detail with the rigorous validation procedures. Along with method validation data, some real-life screening results will be presented to compare an experiment conducted on compounds prepared using the novel hybrid method and those prepared using a more traditional serial dilution method, which endorses the application of the novel method.

Extent of the microbial biosphere in the oceanic crust

We estimate the depth of the 120°C isotherm by constructing crustal thermal gradients based on theoretical and observed conductive heat flux as a function of lithospheric age. We chose the 120°C isotherm because it is close to the upper limit for prokaryotic life, and therefore, the isotherm approximates the maximum depth at which life can persist in the ocean crust. The depth of the potential microbial biosphere increases with lithospheric age from approximately 0.5 to 1 km for 1 Ma lithosphere to as much as 5 km at a subduction age of 180 Ma. We use global models of oceanic plate creation to estimate the volume of crust occupied by the biosphere today and throughout geologic time. Presently, the volume of the ocean crust that is capable of containing life is similar to the volume of the oceans (∼1018 m3). Depending on the model used for the growth of continental crust, the volume of rock available to house the subsurface biosphere may have remained constant or doubled since the Archean. Although the thermal models presented here provide estimates for the potential depth and volume of rock in which microbes may live, the biomass in this volume is not well constrained. Using a previously published model, the prokaryotic biomass in the igneous ocean crust is estimated to exceed that in all aquatic and soil environments and is similar to that in the continental subsurface and in marine sediment. Most of the crustal biomass beneath the sediments is likely contained within the extrusive layer, and this has probably been the case since microbes first colonized the oceanic crust in the Archean.

Lower mantle scattering profiles and fabric below Pacific subduction zones

The Earth's mantle is compositionally evolving principally through the process of mid-ocean ridge basalt production (95% by lithospheric area, but also by way of arc magmatism (> 5%) and continental growth (< 1%) ( Reymer, A., Schubert, G., 1984, Phanerozoic addition rate to the continental–crust and crustal growth, Tectonics, 3, 63–77; Rowley, D.B., 2002, Rate of plate creation and destruction: 180 Ma to present, Geol. Soc. Am. Bull., 114, 927–933). Convection eventually must mix these products back into the mantle, but the details of the mixing process are unknown. We report here new observational data documenting the location of differentiated material in the present-day lower mantle and scattering power profiles with depth. Small-scale (~ 10 km) objects which efficiently scatter short period S waves are present in the mantle lying below the Pacific Ocean rim at depths between 1100 and 1800 km. We also observe a reduction in scattering power with depth indicating that the objects represent bodies richer in differentiated basalt than the surrounding mantle. The scattering objects appear to be deformed to various degrees and usually form clusters separated from each other by a distance of 100 to 200 km. The clusters probably represent folds of the order of 100 km, probably corresponding to early stage of mixing process. Because the scattering power does not increase with depth, neither does a permanent barrier to flow exist in the mid-mantle, nor does the intrinsic density of basalt prevent re-entrainment into mantle flow from the bottom of the mantle.

Temporal variation of oceanic spreading and crustal production rates during the last 180 My

We present a re-evaluation of seafloor spreading and generation rates, mainly based on a direct measurement of the remaining surfaces of oceanic crust and isochron lengths defined in the most recent isochron maps [J.Y. Royer, R.D. Müller, L.M. Gahagan, L.A. Lawyer, C.L. Mayes, D. Nürnberg, J.G. Sclater, A global isochron chart, Tech. Rep. 117, Austin, Univ. of Tex. Inst. for Geophys., 1992; R.D. Müller, W.R. Roest, J.Y. Royer, L.M. Gahagan, J.G. Sclater, Digital isochrons of the world's ocean floor, J. Geophys. Res., 102 (1997), 3211–3214]. Our evaluation of the amount of oceanic crust per unit age {d A/d t} as a function of age, which can be expressed as d A/d t= C o(1− t/ t m), is in fairly good agreement with previous determinations [J.G. Sclater, B. Parsons, C. Jaupart, Oceans and continents: similarities and differences in the mechanisms of heat loss, J. Geophys. Res., 86 (1981) 11,535–11,552; D.B. Rowley, Rate of plate creation and destruction: 180 Ma to present, Geol. Soc. Amer. Bull., 114 (2002) 927–933], with C o=2.850±0.119 km 2 year −1 and t m=180.2±9.7 Ma. Dividing these d A/d t by the ridge lengths L, defined as the isochron length at each epoch allowed us to compute the evolution of global half-spreading rates. These have been roughly constant at 25.9±3.3 mm year −1 for at least the last 150 Ma. We propose that the global seafloor surface generation rate is roughly constant as well, with a mean half-value of 1.298±0.284 km 2 year −1 and varying ±20% with time. This study corroborates the recent conclusion of Rowley [D.B. Rowley, Rate of plate creation and destruction: 180 Ma to present, Geol. Soc. Amer. Bull., 114 (2002) 927–933], of a constant generation rate since 180 Ma, and completely contradicts the commonly accepted idea of high seafloor spreading and surface generation rates during a large part of the Cretaceous. Combining the oceanic surface generation rates derived here with crustal thicknesses deduced from the chemical composition of old oceanic crusts and seismic measurements [E. Humler, C.H. Langmuir, V. Daux, Depth versus age: new perspectives from the chemical compositions of ancient crust, Earth Planet Sci. Lett., 173 (1999) 7–23], the magmatic flux at young (0–80 Ma) oceanic ridges appears to be about 18.1±3.4 km 3 year −1 and was possibly 15% to 30% higher during the Mesozoic. We propose that mantle temperature variation provides an alternative mechanism to spreading rate for the Cretaceous highstand in sea-level and atmospheric CO 2 generation.

A review of flexographic printing plate development

Flexographic printing is increasing in importance. Although a lower cost process, its print quality is now challenging those achieved by gravure printing and lithographic printing. Three of the major driving forces behind the constant improvement of the flexographic print quality are the technologies associated with the printing plate creation, ink formulation and the anilox delivery systems. In this paper, developments in printing plate processing are reviewed. Printing plate processes mainly concern the relevant progress that has been made, in recent years, to the plate type, the plate composition and plate processing.

High‐temperature seafloor hydrothermal circulation over geologic time and archean banded iron formations

Under the assumption of simple plate tectonics with a range of continental growth scenarios, we construct models of global lithospheric heat loss, hydrothermal heat loss and hydrothermal iron flux to the ocean as functions of geologic time from 4.0 Ga to present. The models show that lithospheric heat loss scales with the square root of the plate creation rate, whereas hydrothermal heat loss scales linearly with that rate. Thus during the Archean lithospheric and hydrothermal heat losses were ≈3 and ≈10 times greater than present, respectively. Straightforward extrapolation of hydrothermal Fe flux from the present to the Archean using these models indicates that hydrothermal Fe may not have been sufficient to supply the large Superior‐type Banded Iron Formations deposited between 2.7 and 1.8 Ga.

Rate of plate creation and destruction: 180 Ma to present

One of the primary measures of plate tec- tonics is the history of production of new oceanic lithosphere. As shown by B. Par- sons, a direct estimate of the rate of plate creation can be derived from the area/age versus age distribution of the modern oce- anic lithosphere. Inversion of the most re- cent area versus age data (digital isochrons by R.D. Muller et al.) yields a result that the rate of oceanic plate production has not varied significantly since 180 Ma from a mean rate of 3.4 km 2 /yr. Reconstruction of the cumulative area of subducted litho- sphere over the past 90 m.y. is in excellent agreement with a fixed rate of ridge pro- duction. The conclusion that the rate of ridge production has not varied significant- ly contrasts markedly with most existing es- timates in which the rate is modeled as de- creasing by 50% or more since ca. 100 Ma. A constant rate of ridge production has im- portant implications for models of sea level and p(CO2), among other phenomena that have been linked to variations in global rates of seafloor spreading.