Rhomboid Pattern Research Articles

Reflectance Confocal Microscopy and Dermoscopy of Facial Pigmented and Non-Pigmented Actinic Keratosis Features before and after Photodynamic Therapy Treatment

Actinic keratosis (AK), due to its widespread prevalence, as well as the possibility of progression to an invasive form of squamous cell carcinoma, requires treatment regardless of the clinical stage. New imaging techniques, such as in vivo reflectance confocal microscopy (RCM), significantly increase the accuracy of diagnosis and allow noninvasive evaluation of the therapeutic efficacy of the ongoing treatment. Our objective was to evaluate the prevalence of specific (video)dermoscopy and RCM features of pigmented and classical subtypes of AK before and after photodynamic therapy (PDT) treatment. We included patients with facial grade II AKs (25 pigmented, 275 non-pigmented) were included in the study. Skin lesions were evaluated by (video)dermoscopy and RCM at the baseline and three months after PDT. In classic AK, the most frequent dermoscopic findings were fine wavy vessels (96%), scale (92%), microerosions (48%), and “strawberry” pattern (36%), while pigmented AK was characterized mostly by “rhomboidal pattern” (80%), scale (60%), white globules (48%), “jelly sign”, and superficial pigmentation (40%). RCM’s most characteristic classic AK findings were abnormal honeycomb pattern in the spinous layer, epidermal inflammatory infiltrate, and solar elastosis that were present in 96% of lesions. Pigmented AKs presented mostly with dark central areas of parakeratosis (72%), mottled pigmentation (72%), dermal inflammatory infiltrate (64%), solar elastosis (60%), and abnormal honeycomb pattern in the spinous layer (56%). Dermoscopically, PDT resulted in complete disappearance of the “rhomboidal pattern” in both classical and pigmented AKs, “starburst pattern” and “jelly sign” in classical AKs, and inner gray halo, “rosette sign” and central crust in pigmented AKs. Three months after one PDT session, RCM evaluation showed mostly solar elastosis in both classical and pigmented AK subtypes, epidermal inflammatory infiltrate in classical AKs, and dermal inflammatory infiltrate in pigmented AKs. New noninvasive imaging techniques such as RCM and (video)dermoscopy can help practitioners better visualize the efficacy of the ongoing PDT treatment in either classical or pigmented AK subtypes.

Morphometrical Study of the Lumbar Segment of the Internal Vertebral Venous Plexus in Dogs: A Contrast CT-Based Study.

Simple SummaryThe internal vertebral venous plexus (IVVP) is a valveless venous network running inside the vertebral canal. The objective of this study was to morphometrically describe the IVVP, dural sac, epidural space and vertebral canal of the lumbar segment in dogs with enhanced computerized tomography. Six clinically healthy adult dogs were used for the study. Dorsal reconstructed computed tomography (CT) images showed a continuous rhomboidal morphological pattern for the IVVP. The dural sac was observed as an isodense structure with a rounded shape throughout the vertebral canal. The average percentage area occupied by the IVVP between L1 and L7 vertebrae ranged between 6.3% and 8.9% of the area of the vertebral canal, and the dural sac ranged between 13.8% and 72.2% of the vertebral canal. The epidural space accounted between 27.08% and 86.2% of the lumbar vertebral canal. CT venography is a safe technique that allows adequate visualization and evaluation of the lumbar IVVP and adjacent structures in dogs.The internal vertebral venous plexus (IVVP) is a thin-walled, valveless venous network that is located inside the vertebral canal, communicating with the cerebral venous sinuses. The objective of this study was to perform a morphometric analysis of the IVVP, dural sac, epidural space and vertebral canal between the L1 and L7 vertebrae with contrast-enhanced computed tomography (CT). Six clinically healthy adult dogs weighing between 12 kg to 28 kg were used in the study. The CT venographic protocol consisted of a manual injection of 880 mgI/kg of contrast agent (587 mgI/kg in a bolus and 293 mgI/mL by continuous infusion). In all CT images, the dimensions of the IVVP, dural sac, and vertebral canal were collected. Dorsal reconstruction CT images showed a continuous rhomboidal morphological pattern for the IVVP. The dural sac was observed as a rounded isodense structure throughout the vertebral canal. The average area of the IVVP ranged from 0.61 to 0.74 mm2 between L1 and L7 vertebrae (6.3–8.9% of the vertebral canal), and the area of the dural sac was between 1.22 and 7.42 mm2 (13.8–72.2% of the vertebral canal). The area of the epidural space between L1 and L7 ranged from 2.85 to 7.78 mm2 (27.8–86.2% of the vertebral canal). This CT venography protocol is a safe method that allows adequate visualization and morphometric evaluation of the IVVP and adjacent structures.

Numerical and Experimental Analysis of Labyrinth Seals with Rhomboidal Cells

The labyrinth seals are devices commonly used in turbomachinery to reduce hot gas leakages through engine clearances, which adversely affect the gas turbine performance. For this reason, in the last decades, many in-depth analyses and optimization studies were carried out on this topic using experimental, analytical and numerical approaches. In this work, an innovative rhomboidal pattern is presented, obtained through Computational Fluid Dynamics (CFD) simulations, which is more dissipative than commonly used honeycomb cells. The experiments, performed using a Test Article that reproduces a stage and the next stator of a real low-pressure turbine suitably scaled, allowed to validate the numerical results in a situation that closely approximates the real one of use. The results obtained show that the leakages flow fraction of the total mass flow rate that bypasses the blade, which is 29.4% using a honeycomb pattern, is reduced to 27% with rhomboidal cells. The experimental results also made it possible to verify that the new pattern also behaves well from a thermal point of view, giving rise to temperature differences with respect to the honeycomb of less than 1%.

Tectonics of the Asela‐Langano Margin, Main Ethiopian Rift (East Africa)

AbstractWe provide insights into the tectonics of the Asela‐Langano margin, at the eastern boundary of the central Main Ethiopian Rift, East Africa, by combining field structural data, remote sensing, analysis of the distribution of faults, new dating of faulted material, and analysis of seismicity. The area is characterized by the occurrence of two fault sets: boundary and axial (Wonji) faults, oriented NE‐SW and NNE‐SSW, respectively. Boundary faults show a complex arrangement in the lake Langano area where they display a rhomboidal pattern, due to the presence of NW‐SE‐trending structures, likely related to preexisting transverse fabrics (the so‐called Langano Rhomboidal Fault System). Overall, our analysis supports a structure of the margin characterized by a monocline affected by a series of minor horsts and grabens; this confirms a marked asymmetry of the central Main Ethiopian Rift, with a master fault system on the opposite, western margin. Cumulative paleostress analysis indicates an overall N115°E extension across the Asela‐Langano margin; however, a local variation of the extension direction from axial (Wonji) faults (∼N90°E) to the boundary faults (∼N115°E) can be observed, pointing to a stress reorientation at rift margins. New 14C dating of faulted material and seismicity analysis indicate Late Pleistocene–Holocene and current activity on several normal faults affecting the margin. This suggests that extensional deformation in the central Main Ethiopian Rift is accommodated at the rift margins, with subordinate activity on axial faults, supporting that this rift sector reflects an intermediate stage of rift evolution.

Incipient Tidal Bar and Sill Formation

Estuaries and rivers show dynamic patterns of bars and channels. Mutually evasive ebb‐ and flood‐dominated tidal channels, that is, parallel tidal channels with net sediment transport in opposing directions, give tidal bars their characteristic shape. Here, we study incipient tidal bars with laboratory scale experiments in a periodically tilting flume. Bar patterns evolved from an initial straight channel in an erodible sand bed. Analysis of time‐lapse imagery and bathymetry shows that alternate bars form within 300 tidal cycles. The bars become discrete, recognizable elements after an initial phase characterized by a rhomboid pattern (short and narrow ridges oblique to the channel). Tidal bars show similarities and contrasts with fluvial bars. In general, morphological shapes are similar, including the presence of alternate bars, midchannel bars, and point bars. Sills are superimposed on incipient tidal bars. Sills are narrow and straight and form by flow divergence and thus sediment convergence between alternate bars. This contrasts with rivers, where sills are remnants of alternate bars. Alternate tidal bars grow further by amalgamation of two opposing U‐shaped lobate bars. The dimensions of incipient tidal bars emerge in the first 500 cycles, after which their length and position determine a large‐scale quasiperiodic variation in the estuary width. The results imply that sills are initiated with the onset of tidal bar formation in straight channels and trigger formation of mutually evasive ebb‐ and flood‐dominated channels, thus explaining their ubiquitous occurrence in tidal systems.

Analisis Multi Raster SRTM, Radarsat dan Landsat untuk Karakterisisasi Morfo-struktur dari Geometri Sesar di Daerah Binuang, Kalimantan Selatan

The Binuang area and its surroundings are genetically structural landforms which characterized by cuesta ridge line with curve lineaments pattern on northeast-southwest direction. Geomorphological approach were carried out to determine structural geometry of geological surface using qualitative and quantitative approach on multiple map analysis of remote sensing data. The result of quantitative analysis on elevation data are used to classify heights, slope shape and steepness, lineaments, drainage, and slope aspect. Optical images were classified to determine lithological pattern and boundaries through analysis of band ratios, decorrelation stretch, principal component, and spatial enhancement. The research area are classified into eight class of structural landforms, depicting deformations that occured in western flank of Meratus Mountains. The surface pattern indicates the influence of compressional stress, shown by fold belt with longitudinal characteristic and fault-bounded anticlines on northeast-southwest axis. The formation of main structure pattern on research area was compared with that on strike-slip fault analog model. The resulting correlation factor, R=0.932, shows that both of them are highly correlated. In conclusion, surface structure can possibly form another variation of thrusted mountain belt, such as thrust-dominated restraining bends.Keywords: landsat, SRTM, morphostructure, morphometry, rhomboidal pattern, Meratus.

Analisis Multi Raster SRTM, Radarsat dan Landsat untuk Karakterisisasi Morfo-struktur dari Geometri Sesar di Daerah Binuang, Kalimantan Selatan

The Binuang area and its surroundings are genetically structural landforms which characterized by cuesta ridge line with curve lineaments pattern on northeast-southwest direction. Geomorphological approach were carried out to determine structural geometry of geological surface using qualitative and quantitative approach on multiple map analysis of remote sensing data. The result of quantitative analysis on elevation data are used to classify heights, slope shape and steepness, lineaments, drainage, and slope aspect. Optical images were classified to determine lithological pattern and boundaries through analysis of band ratios, decorrelation stretch, principal component, and spatial enhancement. The research area are classified into eight class of structural landforms, depicting deformations that occured in western flank of Meratus Mountains. The surface pattern indicates the influence of compressional stress, shown by fold belt with longitudinal characteristic and fault-bounded anticlines on northeast-southwest axis. The formation of main structure pattern on research area was compared with that on strike-slip fault analog model. The resulting correlation factor, R=0.932, shows that both of them are highly correlated. In conclusion, surface structure can possibly form another variation of thrusted mountain belt, such as thrust-dominated restraining bends.Keywords: landsat, SRTM, morphostructure, morphometry, rhomboidal pattern, Meratus.

Analisis Multi Raster SRTM, Radarsat dan Landsat untuk Karakterisisasi Morfo-struktur dari Geometri Sesar di Daerah Binuang, Kalimantan Selatan

The Binuang area and its surroundings are genetically structural landforms which characterized by cuesta ridge line with curve lineaments pattern on northeast-southwest direction. Geomorphological approach were carried out to determine structural geometry of geological surface using qualitative and quantitative approach on multiple map analysis of remote sensing data. The result of quantitative analysis on elevation data are used to classify heights, slope shape and steepness, lineaments, drainage, and slope aspect. Optical images were classified to determine lithological pattern and boundaries through analysis of band ratios, decorrelation stretch, principal component, and spatial enhancement. The research area are classified into eight class of structural landforms, depicting deformations that occured in western flank of Meratus Mountains. The surface pattern indicates the influence of compressional stress, shown by fold belt with longitudinal characteristic and fault-bounded anticlines on northeast-southwest axis. The formation of main structure pattern on research area was compared with that on strike-slip fault analog model. The resulting correlation factor, R=0.932, shows that both of them are highly correlated. In conclusion, surface structure can possibly form another variation of thrusted mountain belt, such as thrust-dominated restraining bends.Keywords: landsat, SRTM, morphostructure, morphometry, rhomboidal pattern, Meratus.

Dermoscopy of congenital dermatoses in pediatric age group: An observational study

Objective: To study dermoscopic (DS) patterns of various congenital dermatologic conditions affecting pediatric age group. Background: DS helps to fill gap between histopathology and gross examination, especially in children as they are noncooperative for invasive procedure. It also helps in early detection of malignant change. Methodology: One hundred and forty-nine children with congenital dermatoses were enrolled in a study conducted from August 2017 to January 2018 in dermatology outpatient department (OPD). After proper history and examination, DS images were captured using DermLite DL IV and stored for analysis. Results: One hundred and forty-nine DS images of 22 congenital dermatoses were studied including 80 males and 69 females. Homogenous pattern (80%) was the most common pattern observed in melanocytic nevi (26). Mongolian spots (25) had greenish hue (100%) on DS. Hemangioma (13) and port wine stains (5) showed cherry red vacuoles and red dots against a pink background, respectively. Criss-cross, rhomboid, and lamellate pattern of scales were observed in DS of congenital ichthyosis (8). We also analyzed DS features of bullous and perforating disorders, syndromes, few rare miscellaneous conditions, and hair disorders. Conclusions: DS is a non-invasive diagnostic tool which enables visualization of deeper structures of the skin which are not seen with naked eyes. Melanocytic nevus, if disorganized, indicates increased risk for melanoma in situ. Pattern of scales on DS helps to classify ichthyosis. Regular brown dots suggest wart-like infection in epidermodysplasia verruciformis. DS of monilethrix and short anagen syndrome helps in differentiating from other hairs shaft disorders. Although time consuming, DS is easy to perform, especially in children and it aids to confirm the diagnosis.

Reniformichnus katikatii (New Ichnogenus and Ichnospecies): Continental Vertebrate Burrows from the Lower Triassic, Main Karoo Basin, South Africa

ABSTRACTThe formal ichnotaxonomic assignment of a new ichnogenus and ichnospecies, Reniformichnus katikatii, is presented based on the holotype and several field specimens from the Lower Triassic Katberg Formation in the main Karoo Basin of South Africa. The holotype is an inclined, burrow cast with bilobate base and reniform cross-section. Its width ranges from 12.6 to 14.7 cm, and its height is 5 to 7.4 cm resulting in an aspect ratio of 1.89 to 2.74. The surface preserves 70–180 mm long ridges running parallel to the long axis of the burrow on the upper parts of the walls and lower parts of the dorsum and shorter ridges (average length ∼27 mm) are preserved on the more ventral areas in two opposite orientations, cross-cutting each other in a rhomboid pattern. Burrow fills are passive and consist of slightly bedded, laminated, or massive clastic rocks that are coarser than the host mudstones. The burrow casts are isolated, never occurring in clusters. This simple burrow shows no evidence for branching, spiralling, interconnected tunnels, burrow linings, terminal chambers, or entrances. Preserved in fluvial floodplain mudstone units, the burrows were passively filled by layered, laminated, or massive sand and other coarser clastic sediments. The burrow casts are morphologically similar to unnamed Antarctic ichnotaxa that have been attributed to tetrapods (e.g., therapsids, procolophonids), extending the geographic range of the potential producers of Reniformichnus isp. to continental settings in southern Gondwana. Biostratigraphic evidence on the temporal distribution of Reniformichnus isp. suggests that the trace maker emerged in the aftermath of the Permo-Triassic mass extinction event to successfully burrow throughout the Early Triassic.

Cellular plates with auxetic rectangular perforations

AbstractThe work describes a cellular structure configuration with a rectangular perforation topology exhibiting auxetic (negative Poisson's ratio) in‐plane behaviour. The rectangular voids used in this structure produce a rigid rotating squares effect. Changes in the sizing parameters of aspect ratio, intercell spacing, and number of unit cells are made through non‐dimensional modelling. The effects on the key properties of in‐plane Poisson's ratio, Young's modulus and shear modulus are investigated. Through numerical modelling and experimental testing the auxetic behaviour is confirmed, with increased negative Poisson's ratio values in comparison to rhomboidal patterns of perforations available in open literature.

Numerical simulation of Faraday waves oscillated by two-frequency forcing

We perform a numerical simulation of Faraday waves forced with two-frequency oscillations using a level-set method with Lagrangian-particle corrections (particle level-set method). After validating the simulation with the linear stability analysis, we show that square, hexagonal, and rhomboidal patterns are reproduced in agreement with the laboratory experiments [Arbell and Fineberg, “Two-mode rhomboidal states in driven surface waves,” Phys. Rev. Lett. 84, 654–657 (2000) and “Temporally harmonic oscillons in Newtonian fluids,” Phys. Rev. Lett. 85, 756–759 (2000)]. We also show that the particle level-set’s high degree of conservation of volume is necessary in the simulations. The numerical results of the rhomboidal states are compared with weakly nonlinear analysis. Difficulty in simulating other patterns of the two-frequency forced Faraday waves is discussed.

The longest faun tail forming dreadlocks with underlying spina bifida occulta

Spina bifida is a developmental anomaly characterized by defective closure of the bony encasement of the spinal cord through which the spinal cord and meninges may or may not protrude. We report a rare case of a very long faun tail, which was in the form of a 20 inch long tail originating from the lumbosacral area in a rhomboidal pattern, measuring 10 x 8 inches. The case is being reported for its rare presentation of a 20 inch long faun tail with underlying spina bifida occulta.

Fever and rhomboid target lesion in decompensated cirrhosis

A 53-year-old woman with Child-Pugh B, hepatitis C virus-related cirrhosis presented with a 3 day history of high fever (peak 39·5°C) and a non-itchy rash. On admission, physical examination showed mild ascites, and a temperature of 38·5°C, a pulse rate of 88 beats per min, and a respiratory rate of 18 breaths per min were recorded. Many large (about 15 cm diameter) target lesions were present on the patient’s trunk and arms and legs, seen as concentric rings of a dull red, pink, or violet colour surrounding a clear centre (fi gure). No mucosal lesions were noted. Laboratory tests recorded a white-blood-cell count of 12×109 cells per L and a C-reactive protein concentration of 3·4 mg/L. Abdominal ultrasound confi rmed the presence of ascites, and echocardiography did not indicate endocarditis. Treatment with oral levofl oxacin was started; 2 days later, the patient’s fever was reduced, all lesions gradually ameliorated acquiring a rhomboid aspect, and liver decompensation diminished progressively. Meanwhile, two blood cultures yielded Grampositive bacteria identifi ed as Erysipelothrix rhusiopathiae. The patient attended the outpatient’s clinic at the Clinical and Molecular Hepatology Unit of the University Hospital of Messina 1 month after discharge from hospital and every 3 months thereafter. At the last visit (January, 2012) no signs of worsening liver disease were noted and the skin lesions had not reappeared. E rhusiopathiae is a common commensal or pathogen of many vertebrate and invertebrate species. Pigs are a major reservoir. Human disease is mainly an occupationally acquired zoonosis. The portal of entry is typically a puncture wound or abrasion on the hand; however, it can also be acquired from eating contaminated food. The patient does not work with animals and denied any injuries while preparing food. However, the week before she became unwell she ate raw pork meat. Liver dysfunction could be associated with E rhusiopathiae bacteraemia because of the noted impairment of reticuloendothelial function in the patient. Three clinical forms of infection with E rhusiopathiae have been reported in human beings: a localised cutaneous form, or erysipeloid of Rosenbach; a diff use cutaneous form; and a bacteraemic form that occurs with or without endocarditis. The diff use cutaneous form constitutes a rare situation in which violaceous cutaneous lesions can arise at remote areas as widespread urticaria with the rhomboid pattern characteristic of swine erysipelas. In our patient, the pattern was associated with bacteraemia without endocarditis.

Paleobiology of the Crustacean Trace FossilSpongeliomorpha ibericain the Miocene of Southeastern Spain

The trace fossil Spongeliomorpha iberica locally occurs in the Tortonian (Upper Miocene) marine strata of the Fortuna ba− sin in southeastern Spain, and its excellent preservation state allows a reliable reconstruction of its main morphologic fea− tures. The burrow systems are branched (but not anastomosing), and they include numerous, short, blind tunnels. The bur− row walls are strongly ornamented with bioglyphs displaying a rhomboidal pattern, consisting mostly of individual “Y”−shaped scratches. Smaller, secondary bioglyphs consist of sets of less incised transverse scratches. These features allow us to assign the ichnospecies to a decapod crustacean, most likely an alpheid or thalassinidean shrimp. The burrow appar− ently served as a refuge for the inhabitant, which fed upon microorganisms growing on the walls of the burrow by means of scraping the interior surfaces with the maxillipeds or other mouth parts. It is also likely that the shrimp used the multiple blind tunnels to store organic material (probably plant detritus) to be used for later consumption. The crustaceans colonized mud firmgrounds, which were formed by erosion during a rapid sea−level fall. Thus, the burrows occur in direct association with erosional regressive surfaces and therefore are good stratigraphic indicators of abrupt paleoenvironmental change. Key wor ds: Arthropoda, Crustacea, Decapoda, Spongeliomorpha, ichnology, trace fossil, bioglyph, Miocene, Spain.

Rhomboid beach pattern: A laboratory investigation

The formation of beach rhomboid pattern by swash is investigated experimentally. This centimeter‐scale structure is classically interpreted as the mark of stationary gravity waves generated by obstacles in supercritical flows. However, thanks to the use of water‐based fluids of various viscosity, our experiments show that a rhomboid pattern can develop in subcritical flows. Its angle is primarily a function of the Froude number, as suggested by Woodford (1935), but our data do not support his classical model, nor do they support any of the existing theories. The slowness of the rhombus motion indicates that it is not simply the mark of a hydraulic phenomenon but rather results from the coupling between the water flow and sediment transport.

Stability of bedforms in laminar flows with free surface: from bars to ripples

The present paper is devoted to the formation of sand patterns by laminar flows. It focuses on the rhomboid beach pattern, formed during the backswash. A recent bedload transport model, based on a moving-grains balance, is generalized in three dimensions for viscous flows. The water flow is modelled by the full incompressible Navier–Stokes equations with a free surface. A linear stability analysis then shows the simultaneous existence of two distinct instabilities, namely ripples and bars. The comparison of the bar instability characteristics with laboratory rhomboid patterns indicates that the latter could result from the nonlinear evolution of unstable bars. This result, together with the sensibility of the stability analysis with respect to the parameters of the transport law, suggests that the rhomboid pattern could help improving sediment transport models, so critical to geomorphologists.

Nanostructuring Rh(110) Surfaces by Ion Etching

ABSTRACTThe ion irradiation of the Rh(110) surface results in the self-organised formation of various nano-structured morphologies like ripples, mounds, pyramids which have been thoroughly studied as a function of the incidence angle and of the impact energy of the impinging ions. A study of the evolution of the surface ripples at various impact energies above the hot-spot threshold, has been rationalized in terms of a contribution due to an ion-induced surface diffusion mechanism. In the very low ion incidence regime, where the formation of hot spots following ion impact is inhibited, the formation of a rhomboidal pyramid pattern is singled out and attributed to the predominant reorganization of surface adatom and vacancies produced in the topmost surface layers. The metastable rhomboidal pyramid pattern, was recently proven to have extraordinary chemical reactivity since it is endowed with a very high density of undercoordinated step sites runnin along the very open <1-12> azimuthal direction.

Changes in the EEG Spectrum and Subjective Characteristics of the General State after Stimulation with Variable Frequency Photic Stimuli with Two Types of Organization

Two sinusoidal signals, one with a constant frequency of 13 Hz and the other with a frequency continuously changing from 1 to 6 Hz and back, were presented simultaneously to subjects through spectacles with light-emitting diodes either to both eyes as a product (amplitude modulation of a constant frequency by a variable one) or to each eye separately. Both kinds of variable frequency exposure revealed a rhomboid pattern of the resonance activation of the EEG spectrum, similar to the spectral dynamics of a signal subject to amplitude modulation. This testifies to the key role of EEG amplitude modulation in the responses of the nervous system to variable frequency rhythmic stimuli. Both types of photic stimulation led to a substantial increase in EEG spectral density and improved the subjects' self-rating of the overall state of well-being, activity, and mood. In addition, separate stimulation of each eye led to an improvement in the anxiety and exercise performance indices (the Luscher color test) and a significant correlation between the intensity of EEG responses and changes in the general state. These differences are explained in terms of the involvement of the interhemispheric interaction mechanisms in the processing of complex rhythmic signals by the brain.

Development of accommodation zones in the Gulf of Suez-Red Sea rift, Egypt

Basement rocks on the margins of the late Oligocene-Miocene Gulf of Suez-Red Sea rift system contain penetrative west-northwest, northwest, and north-south Precambrian structures, including foliations, fractures, faults, and regional sinistral shear zones. These have been reactivated during the Cenozoic rifting and have exerted fundamental controls on both rift-border fault geometries and the location of accommodation zones within the rift system. Two accommodation zones, the Zaafarana accommodation zone in the northern Gulf of Suez and the Duwi accommodation zone in the northwestern Red Sea rift margin, have been analyzed in detail. In both accommodation zones, the southwest-dipping, eastern rift-border faults (EBFs) consist of reactivated, Precambrian north-south and northwest foliations and fractures, which link together forming a rhomboidal zigzag fault pattern. Each EBF intersects a Precambrian shear zone then splays and loses displacement. In contrast, both of the northeast-dipping, western border faults (WBFs) consist of a reactivated fault segment colinear with a Precambrian shear zone, and this is hard-linked to a north-south-north-northeast-oriented, less well developed fault system via a discrete transfer fault. The change in dip direction of the half grabens is related to initial reactivation of preexisting regional, intersecting north-south and west-northwest Precambrian shear zones by late Oligocene-early Miocene N60 degreesE extension. This configuration allows initial left-lateral and right-lateral oblique-slip on the north-south and west-northwest zones, respectively. We present new models for the localization of the accommodation zones and for the development of the rift half-graben architectures.