Ridge Length Research Articles

Morphological differences between two closely related East Asian flatfish species of the genus Pleuronichthys, with particular emphasis on growth-related changes

Morphological differences, including growth-related changes, were examined in two closely related East Asian flatfish species, Pleuronichthys lighti and Pleuronichthys cornutus. Body measurements of both species indicated frequent growth-related proportional changes, head length, pelvic fin length (both fins), eye diameter (both eyes), inter-orbital ridge length and the lengths of both jaws all showing relative decreases with growth. On the other hand, whereas caudal fin length became relatively shorter and snout length relatively greater with growth in P. lighti, those proportions remained unchanged with growth in P. cornutus. Conversely, although body depth became relatively greater and the longest dorsal and anal fin rays relatively shorter with growth in P. cornutus, those proportions remained unchanged with growth in P. lighti. Counts of scales below the lateral line and gill rakers both tended to increase with growth in P. cornutus, but remained stable in P. lighti. New key characters to distinguish between the two species included ocular side pectoral fin length and the area ratio between the upper and lower eyes. The ocular side pectoral fin of P. cornutus was generally longer than in P. lighti, with plots of the fin proportions in the two species showing modest separation. In addition, because both the horizontal and vertical diameters of the upper eye of P. cornutus were generally greater than those of P. lighti, graphical representation of the relationship between the upper and lower eye areas showed almost complete separation of the two species.

An Approach to Time-Frequency Analysis With Ridges of the Continuous Chirplet Transform

We propose a time-frequency representation based on the ridges of the continuous chirplet transform to identify both fast transients and components with well-defined instantaneous frequency in noisy data. At each chirplet modulation rate, every ridge corresponds to a territory in the time-frequency plane such that the territories form a partition of the time-frequency plane. For many signals containing sparse signal components, ridge length and ridge stability are maximized when the analysis kernel is adapted to the signal content. These properties provide opportunities for enhancing signal in noise and for elementary stream segregation by combining information across multiple analysis chirp rates.

Changes in Melanin and Melanocytes in Mottled Hypopigmentation after Low-Fluence 1,064-nm Q-Switched Nd:YAG Laser Treatment for Melasma.

Dear Editor: Melasma is a common acquired hyperpigmentary disorder of the face, but its treatment remains challenging. A procedure called that uses a low-energy 1064-nm Q-switched Nd:YAG laser was recently introduced for the treatment of melasma, demonstrating good results1,2,3. However, the possibility of mottled hypopigmentation is a major concern with this treatment, because it rarely recovers spontaneously4. The underlying mechanisms of mottled hypopigmentation are not completely understood. Whether the hypopigmentation is caused by reduced pigmentation with intact melanocytes or a decrease or absence of melanocytes remains to be elucidated. Therefore, this study investigated the changes in melanin and melanocytes in hypopigmented lesions that develop after low-fluence 1,064-nm Q-switched Nd:YAG laser treatment for melasma. This study was approved by the institutional review board of Ajou University Hospital (AJIRB-MED-KSP-12-374). Patient 1, a 41-year-old woman with Fitzpatrick skin type IV, presented with typical mottled hypopigmentation after treatment with 1,064-nm Q-switched Nd:YAG laser for melasma (Fig. 1A). The duration of hypopigmentation was 7 years. Skin biopsies were obtained from the hypopigmented, hyperpigmented (i.e., melasma), and adjacent perilesional normal skin areas. Hematoxylin and eosin and Fontana-Masson staining as well as immunohistochemical staining using melanocyte-specific markers including monoclonal antibodies against human gp100 (NKI/ beteb; Monosan, Uden, the Netherlands), tyrosinase (Thermo Scientific, Fremont, CA, USA), and microphthalmia-associated transcription factor (MITF; Leica Biosystems, Newcastle, UK) were performed. The numbers of MITF+ melanocytes per 1-mm length of rete ridge were counted. The expression levels of gp100 and tyrosinase were measured as the ratio of stained area to measured epidermal area. Fig. 1 (A) Mottled hypopigmentation developing after laser toning for melasma treatment in a 41-year-old woman with Fitzpatrick skin type IV. Hypopigmented, hyperpigmented (i.e., melasma), and adjacent perilesional normal skin were evaluated. Circles indicate ... The general histological findings of the hypopigmented skin were unremarkable. There was no collagen remodeling or scarring. Fontana-Masson staining demonstrated the almost complete absence of melanin pigment in hypopigmented skin (Fig. 1B). The number of melanocytes, as determined by MITF expression, was not substantially different in lesional skin (n=4) compared to perilesional normal skin (n=5) or melasma skin (n=3). Consistently, tyrosinase level was not lower in lesional skin than perilesional normal skin but was higher than that in melasma skin as expected. Interestingly, gp100 expression was higher in the hypopigmented lesion than perilesional normal skin and even melasma skin. Similar findings were observed in patient 2, a 49-year-old woman with Fitzpatrick skin type III who presented with typical mottled hypopigmentation after laser toning for 1 year (Fig. 2A). Lesional skin biopsy showed the complete absence of melanin pigment in hypopigmented skin. However, there was no reduction in the number of melanocytes, and gp100 expression was elevated (Fig. 2B). Fig. 2 (A) A 49-year-old woman with Fitzpatrick skin type III presented with typical mottled hypopigmentation after laser toning for 1 year. Circle indicates biopsy sites of the hypopigmented lesion. (B) Lesional skin biopsy showed the complete absence of melanin ... The results of the present study clearly demonstrate that the histologic features of laser toning-induced hypopigmentation are characterized by almost destroyed melanosome pigments and a preserved the number of melanocytes. However, it is unclear whether the number of melanocytes is reduced in the hypopigmented skin. One study indicates hypopigmentation might be due to melanocytopenia5. However, in that study, lesional skin was not compared with adjacent perilesional normal skin. The other studies suggest the number of melanocytes in hypopigmented skin is normal6,7. In the present study, there was no difference in the mean numbers of MITF-stained melanocytes between lesional skin and perilesional normal skin. Interestingly, we noticed that the levels of the structural protein gp100 were preserved and rather elevated in lesional skin compared to perilesional normal skin. Moreover, in patient 1, gp100 levels of hypopigmented skin were clearly elevated compared to that in hyperpigmented skin. Although the reason for this result is unclear, these findings nonetheless suggest the melanogenic activity in the melanocytes was impaired and the cells failed to produce fully matured melanosomes. Considering that the proposed action mechanism of laser toning is subcellular selective photothermolysis of melanosomes and not melanocytes, it is speculated that melanocytes survived but were functionally downregulated such that they did not produce fully matured melanosomes. The cumulative dose of repetitive laser treatment may affect melanocyte function, resulting in the development of hypopigmentation. Therefore, treatment activating or stimulating melanogenesis in the melanocytes would be required. To this end, treatment with focused narrowband ultraviolet B therapy has been used with some success8. In conclusion, laser toning-induced hypopigmentation is characterized by almost destroyed melanosome pigments and a preserved number of melanocytes, which seem to be functionally downregulated not to produce fully matured melanosomes. Thus, early intervention aiming to restore melanocyte function would be required.

Possible Involvement of Keratinocyte Growth Factor in the Persistence of Hyperpigmentation in both Human Facial Solar Lentigines and Melasma.

Possible Involvement of Keratinocyte Growth Factor in the Persistence of Hyperpigmentation in both Human Facial Solar Lentigines and Melasma.

Late Noachian and early Hesperian ridge systems in the south circumpolar Dorsa Argentea Formation, Mars: Evidence for two stages of melting of an extensive late Noachian ice sheet

The Dorsa Argentea Formation (DAF), extending from 270°–100° E and 70°–90° S, is a huge circumpolar deposit surrounding and underlying the Late Amazonian South Polar Layered Deposits (SPLD) of Mars. Currently mapped as Early-Late Hesperian in age, the Dorsa Argentea Formation has been interpreted as volatile-rich, possibly representing the remnants of an ancient polar ice cap. Uncertain are its age (due to the possibility of poor crater retention in ice-related deposits), its mode of origin, the origin of the distinctive sinuous ridges and cavi that characterize the unit, and its significance in the climate history of Mars. In order to assess the age of activity associated with the DAF, we examined the ridge populations within the Dorsa Argentea Formation, mapping and characterizing seven different ridge systems (composed of nearly 4,000 ridges covering a total area of ~300,000km2, with a cumulative length of ridges of ~51,000km) and performing crater counts on them using the method of buffered crater counting to determine crater retention ages of the ridge populations. We examined the major characteristics of the ridge systems and found that the majority of them were consistent with an origin as eskers, sediment-filled subglacial drainage channels. Ridge morphologies reflect both distributed and channelized esker systems, and evidence is also seen that some ridges form looping moraine-like termini distal to some distributed systems. The ridge populations fall into two age groups: ridge systems between 270° and 0° E date to the Early Hesperian, but to the east, the Promethei Planum and the Chasmata ridge systems date to the Late Noachian. Thus, these ages, and esker and moraine-like morphologies, support the interpretation that the DAF is a remnant ice sheet deposit, and that the esker systems represent evidence of significant melting and drainage of meltwater from portions of this ice sheet, thus indicating at least some regions and/or periods of wet-based glaciation. The Late Noachian and Early Hesperian ages of the ridge systems closely correspond to the ages of valley network/open basin lake systems, representing runoff, drainage and storage of liquid water in non-polar regions of the surface of Mars. Potential causes of such wet-based conditions in the DAF include: 1) top-down melting due to atmospheric warming, 2) enhanced snow and ice accumulation and raising of the melting isotherm to the base of the ice sheet, or 3) basal melting associated with intrusive volcanism (volcano-ice interactions). The early phase of melting is closely correlated in time with valley network formation and thus may be due to global atmospheric warming, while the later phase of melting may be linked to Early Hesperian global volcanism and specific volcano-ice interactions (table mountains) in the DAF. Crater ages indicate that these wet-based conditions ceased by the Late Hesperian, and that further retreat of the DAF to its present configuration occurred largely through sublimation, not melting, thus preserving the extensive ridge systems. MARSIS radar data suggest that significant areas of layered, potentially ice-rich parts of the Dorsa Argentea Formation remain today.

Observation of sand waves in the Taiwan Banks using HJ-1A/1B sun glitter imagery

This study focuses on the large sand waves in the Taiwan Banks. Our goals are to observe the sand waves as completely as possible, to obtain their direction, wavelength, density, and ridge length, to analyze their spatial distributions, and to understand the effects of the current field and water depth on the sand waves. This study demonstrates the possibility of using HJ-1A/1B sun glitter imagery with a large swath width and rapid coverage in studying sand waves. Six cloud-free HJ-1A/1B optical images with sun glitter signals received during 2009 to 2011 were processed. The sand waves were mapped based on their features in the images; their direction, wavelength, density, and ridge length were measured and analyzed. We identified 4604 sand waves distributed in an area of 16,400 km2. The distributions of sand waves and their characteristics were analyzed, and the differences of sand waves between the northwestern subregion and the southeastern subregion are reported. Further analysis and discussion of the relationships between spatial distribution of the sand waves and both the tidal current field from a numerical simulation and water depth led to some interesting conclusions. The current field determines the orientation of the sand wave, while the hydrodynamic conditions and water depth influence the shape, size, and density of sand waves to a certain degree.

Plate convergence west of Patagonia and the Antarctic Peninsula since 61 Ma

A new plate kinematic model portrays plate motions immediately west and south of Drake Passage in the southeast Pacific Ocean. Overall intermediate-to-slow rate spreading generated oceanic lithosphere as the Phoenix plate diverged from the Antarctic plate. The model shows a history of Phoenix plate motion that is interpretable as having been affected by a northeast-increasing gradient in the slab pull force since chron 18 (39Ma), during which time newer, less dense lithosphere was subducting in the southwest than in the northeast. The model allows first calculations of Phoenix–Farallon (Nazca) plate motion parameters in the south Pacific plate circuit. Using these parameters, it is possible to show that the simplest assumptions about the ridge's segmentation, length and migration are consistent with existing suggestions of its location from consideration of slab window-related volcanism at sites in South America around 50 and 20Ma. The parameters thus define ridge locations that can be used to define which plates were subducting beneath South America and the Magallanes and Antarctic plates, and when. We consider the relationships between the plate convergence rate, obliquity and the history of magmatism on the Antarctic Peninsula and at the North Patagonian batholith, showing that magmatic pulses can be related to accelerations in the plate convergence rate. Between these settings, Phoenix–South American plate motion was almost parallel to the Fuegian trench. Here, magmatism in Paleocene to early Miocene times must be related to the presence of a slab subducted beneath the region by the less oblique collision further north. Later magmatism can be related to migration of the Phoenix–Farallon ridge and Phoenix–Farallon–Antarctic triple junction into the area south of the Fuegian margin, which brought it into slow low-obliquity convergence with first Farallon and then Antarctic plate lithosphere.

Further Sensitivities of Orographic Precipitation to Terrain Geometry in Idealized Simulations

Abstract This study examines how variations to the nondimensional mountain height Ĥ and the horizontal aspect ratio β of a straight ridge and a concave ridge influence orographic precipitation. An idealized three-dimensional model is used to simulate a moist flow impinging upon these two ridges with Ĥ = 0.66–2.0 and β = 1.0–8.0. The concave ridge generates substantially more precipitation than the straight ridge via an established precipitation-enhancing funneling mechanism near the ridge vertex when the flow is unblocked. Based on previous work, it was hypothesized that when the approaching flow becomes blocked, the strength of the precipitation enhancement by the concave ridge relative to the straight ridge becomes negligible. This study reveals that, if Ĥ is sufficiently large to induce flow reversal on the windward slope, then a secondary circulation develops that is strengthened by the concave ridge with a subsequent enhancement of precipitation. It is also shown that the competing effects of the ridge length and width render the strength of the precipitation enhancement largely insensitive to β. A flow regime diagram for the straight ridge and the concave ridge is also constructed to illustrate the sensitivity of the critical Ĥ value for flow regime transition to changes in the terrain geometry; variations to the low-level relative humidity are also explored.

A revision of the Upper Cretaceous lepidosirenid lungfishes from the Quseir Formation, Western Desert, central Egypt

ABSTRACTWe evaluate new lungfish remains from the Upper Cretaceous Quseir Formation in the Western Dessert of southern Egypt. Taxa include Lavocatodus protopteroides, L. humei, L. giganteus, and Protopterus nigeriensis. We treat Lavocatodus as members of Lepidosirenidae based on the presence of a well-defined medial articular surface, in the absence of a symphyseal surface of corresponding prearticular bones. Material of L. protopteroides represents the first example of an adult specimen, supporting the retention of the species as valid, and not a junior synonym of L. humei. Specimens of L. humei are the most abundant in the assemblage, and all exhibit the medial articular surface, a feature that is absent from specimens of Ceratodus; therefore, we reassign additional specimens of ‘C.’ humei to Lavocatodus. New specimens of L. giganteus extend the temporal and spatial ranges of the species (the type material of L. giganteus is from Paleocene deposits of In Farghas, Mali). Finally, a new specimen of Protopterus represents the oldest record of the genus in Egypt. The prearticular is confidently assigned to Protopterus based on the presence of only three ridges on the tooth plate, a medial symphyseal suture, a coronoid process, and a shallow tooth crown plus prearticular depth. We further assign it to P. nigeriensis based the length and merger of tooth ridges. Furthermore, the oldest Cenomanian specimens reported from the Sudan Wadi Milk Formation are assigned to P. nigeriensis, which would extend the temporal range of P. nigeriensis by roughly 14 Ma.

Retinopathy of Prematurity Vessel and Ridge Parameters Measurement by Unsupervised Algorithm

The Retinopathy of Prematurity (ROP) is an ocular pathological disorder of the retinal blood vessels in premature infants and low birth weight infants. It is essential that those caring for premature infants should know who is at risk of ROP and their severity stage. It is also important that when screening must begin and how often these infants need to be examined otherwise the progression lead most severe stage and can cause blindness. The contrast stretching method has been utilized to enhance the ROP color image. Then an automatic method Isotropic Un-decimated Wavelet Transform (IUWT) has been proposed to extract the abnormal retinal blood vessel and measure its width and tortuosity. The ridge formation of this pathological disorder has also been obtained by the IUWT. The quantitative measurements of mean diameter, standard deviation, tortuosity, length of retinal blood vessel and ridge have been considered and computed the exact severity stage of ROP. The effectiveness of the proposed method has been verified through machine vision techniques and the results obtained are encouraged by experts. Automatic ROP screening system comprises several advantages, like a substantial time reduction of ophthalmologists in diagnosis, a non ophthalmologist can provide stage of ROP, improving the sensitivity of the test and a better accuracy in diagnosis.

Interferon-γ/CCR5 expression in invariant natural killer T cells and CCL5 expression in capillary veins of dermal papillae correlate with development of psoriasis vulgaris

There have been extensive studies regarding which types of T lymphocytes are involved in psoriasis vulgaris (PV). However, it has remained unclear which types of T lymphocytes might directly contribute to psoriasiform epidermal and vascular hyperplasia. To understand the role of T-cell receptor (TCR)Vα24+ invariant natural killer (iNK)T cells in the development of PV. Seventeen patients were enrolled in this study. Using biopsy samples of PV plaques, TCRVα24(+) iNKT cells were investigated regarding their cytokine production to understand their roles in development of disease. The number of interferon (IFN)-γ+ iNKT cells correlated with the length of the psoriasiform hyperplasia rete ridge and the Psoriasis Area and Severity Index. IFN-γ+ iNKT cells in psoriatic skin exhibited higher C-C chemokine receptor (CCR)5 expression, and the amount of C-C chemokine ligand (CCL)5, a ligand for CCR5, was increased in capillary veins of psoriasis plaques. CCR5+ iNKT-cell numbers significantly correlated with the number of capillary vein endothelial cells expressing CCL5 in PV. Furthermore, the number of CCL5+ capillary veins correlated with the maximum rete ridge length. IFN-γ/CCR5 expression in iNKT cells and CCL5 expression in vessels of dermal papillae correlate with the development of psoriasiform hyperplasia and microabscess. We propose that these iNKT cells may become useful targets for development of novel therapeutic approaches to PV.

Tectonic and magmatic control of hydrothermal activity along the slow‐spreading Central Indian Ridge, 8°S–17°S

AbstractThe complex geology and expansive axial valleys typical of slow‐spreading ridges makes evaluating their hydrothermal activity a challenge. This challenge has gone largely unmet, as the most undersampled MOR type for hydrothermal activity is slow spreading (20–55 mm/yr). Here we report the first systematic hydrothermal plume survey conducted on the Central Indian Ridge (CIR, 8°S–17°S), the most extensive such survey yet conducted on a slow‐spreading ridge. Using a combined CTD/Miniature Autonomous Plume Recorder (MAPR) package, we used 118 vertical casts along seven segments of the CIR (∼700 km of ridge length) to estimate the frequency of hydrothermal activity. Evidence for hydrothermal activity (particle and methane plumes) was found on each of the seven spreading segments, with most plumes found between 3000 and 3500 m, generally <1000 m above bottom. We most commonly found plumes on asymmetric ridge sections where ultramafic massifs formed along one ridge flank near ridge‐transform intersections or nontransform offsets. The estimated plume incidence (ph) for axial and wall casts (ph=0.30, 35 of 118 casts) is consistent with the existing global trend, indicating that the long‐term magmatic budget on the CIR is the primary control on the spatial frequency of hydrothermal venting. Our results show that the tectonic fabric of the CIR strongly determines where hydrothermal venting is expressed, and that using only near‐axial sampling might underestimate hydrothermal activity along slow‐spreading and ultraslow‐spreading ridges. Serpentinization is a minor contributor to the plume inventory, based on 15 profiles with methane anomalies only, predominantly at depths above the local valley walls.

Hydrothermal sulfide accumulation along the Endeavour Segment, Juan de Fuca Ridge

Hydrothermal sulfide deposits that form on the seafloor are often located by the detection of hydrothermal plumes in the water column, followed by exploration with deep-towed cameras, side-scan sonar imaging, and finally by visual surveys using remotely-operated vehicle or occupied submersible. Hydrothermal plume detection, however, is ineffective for finding hydrothermally-inactive sulfide deposits, which may represent a significant amount of the total sulfide accumulation on the seafloor, even in hydrothermally active settings. Here, we present results from recent high-resolution, autonomous underwater vehicle-based mapping of the hydrothermally-active Endeavour Segment of the Juan de Fuca Ridge, in the Northeast Pacific Ocean. Analysis of the ridge bathymetry resulted in the location of 581 individual sulfide deposits along 24 km of ridge length. Hydrothermal deposits were distinguished from volcanic and tectonic features based on the characteristics of their surface morphology, such as shape and slope angles. Volume calculations for each deposit results in a total volume of 372,500 m3 of hydrothermal sulfide–sulfate–silica material, for an equivalent mass of ∼1.2 Mt of hydrothermal material on the seafloor within the ridge's axial valley, assuming a density of 3.1 g/cm3. Much of this total volume is from previously undocumented inactive deposits outside the main active vent fields. Based on minimum ages of sulfide deposition, the deposits accumulated at a maximum rate of ∼400 t/yr, with a depositional efficiency (proportion of hydrothermal material that accumulates on the seafloor to the total amount hydrothermally mobilized and transported to the seafloor) of ∼5%. The calculated sulfide tonnage represents a four-fold increase over previous sulfide estimates for the Endeavour Segment that were based largely on accumulations from within the active fields. These results suggest that recent global seafloor sulfide resource estimates, which were based mostly on the sizes and distribution of hydrothermally-active deposits, may be similarly underestimating the amount of sulfide along the global submarine neovolcanic zones.

Effect of ridge-ridge interactions in crumpled thin sheets.

We study whether and how the energy scaling based on the single-ridge approximation is revised in an actual crumpled sheet, namely, in the presence of ridge-ridge interactions. Molecular dynamics simulation is employed for this purpose. In order to improve the data quality, modifications are introduced to the common protocol. As crumpling proceeds, we find that the average storing energy changes from being proportional to one-third of the ridge length to a linear relation, while the ratio of bending and stretching energies decreases from 5 to 2. The discrepancy between previous simulations and experiments on the material-dependence for the power-law exponent is resolved. We further determine the average ridge length to scale as 1/D(1/3), the ridge number as D(2/3), and the average storing energy per unit ridge length as D(0.881) where D denotes the volume density of the crumpled ball. These results are accompanied by experimental proofs and are consistent with mean-field predictions. Finally, we extend the existent simulations to the high-pressure region and verify the existence of a scaling relation that is more general than the familiar power law at covering the whole density range.

Optimize Selected of Anti-Attrition Ridge Parameters through Numerical Simulation in CFB Boiler Blended with Waste Sludge

Combustion in boiler blended with waste sludge can cause serious abrasion in the furnace. In this paper, Fluent6.3 was applied to establish three-dimensional numerical combustion model based on k-ε turbulence equations and Lagrangian stochastic particle trajectory to analyze a CFB (Circulating Fluidized Bed) boiler of a power plant in Guangdong province. The results show that anti-attritions will break the ring-core adherent regurgitation of the particles thus reducing erosion of particles made to the furnace wall. Furthermore, a setting of three anti-attrition ridges can prolongate the life of the wall by 2.49 times. Increasing numbers and the length of ridges are beneficial to wall, which should be limited shorter than 150mm duo to heat tube slagging, and implementing a shape of trapezoid instead of rectangle all are derived as enhancements to the feature of anti-attrition of CFB.

Endoscopic and Three-Dimensional Radiographic Imaging of the Pterygopalatine and Infratemporal Fossae

We sought to define the surgical endoscopic anatomy of the pterygopalatine fossa (PPF) and infratemporal fossa (ITF) through endoscopic cadaver dissections and radiographic imaging analysis. Eleven fresh cadavers were submitted to computed tomography (CT) and endoscopic dissection. We used 3-dimensional (3-D) CT reconstruction and endoscopic video imaging for analysis of the bony and soft tissue landmarks. One fixed cadaver head was grossly dissected to confirm the endoscopic anatomic findings. The CT and 3-D CT reconstruction measurements between the pterygoid canal and the foramen rotundum averaged 4.36 mm and 5.09 mm, respectively. An osseous ridge (pterygoid ridge) was identified on the anterior face of the pterygoid process as a novel identifiable anatomic landmark in all of the specimens. The average length of the pterygoid ridge on 3-D CT reconstruction was 7.84 mm. The internal maxillary artery entered the PPF posteromedial to the temporalis tendon and anterolateral to the lateral pterygoid muscle. The average distance from the anterior edge of the lateral pterygoid plate to the foramen ovale was 17.1 mm. The pterygoid ridge is a novel and reliable osseous landmark that could assist surgeons during endoscopic surgery on the PPF and ITF. The neurovascular and muscular anatomic relationships were characterized for both the PPF and the ITF.

In vivo imaging of lentigo with confocal laser scanning microscopy

Objective To assess the microscopic features of lentigo by using in vivo confocal laser scanning microscopy (CLSM).Methods This study included 30 patients clinically diagnosed with solar lentigo and 10 patients with lentigo simplex.Lentigo lesions and perilesional normal skin were examined by in vivo CLSM.Tissue specimens were also obtained from lesional and perilesional normal skin and subjected to routine histopathologic examination.Results The CLSM features of lentigo were mainly observed at the dermo-epidermal junction.In all of these cases of lentigo,there was an increase in the length and number of rete ridges,with a marked hyperpigmentation of the basal layer.Several distinct microscopic patterns were observed,such as extended,irregularly shaped papillary dermis surrounded by highly refractile cells (presumed to be basal keratinocytes).Histopathologically,there was an infiltrate of a small quantity of melanophages and lymphocytes in superficial dermis.Conclusion As far as lentigo lesions are concerned,CLSM images are consistent with histopathological findings.

Convergence of tectonic reconstructions and mantle convection models for significant fluctuations in seafloor spreading

For 50 years of data collection and kinematic reconstruction efforts, plate models have provided alternative scenarios for plate motions and seafloor spreading for the past 200 My. However, these efforts are naturally limited by the incomplete preservation of very old seafloor, and therefore the time-dependence of the production of new seafloor is controversial. There is no consensus on how much it has varied in the past 200 My, and how it could have fluctuated over longer timescales. We explore how seafloor spreading and continental drift evolve over long geological periods using independently derived models: a recently developed geodynamic modelling approach and state-of-the-art plate reconstructions. Both kinematic reconstructions and geodynamic models converge on variations by a factor of 2 in the rate of production of new seafloor over a Wilson cycle, with concomitant changes of the shape of the area–age distribution of the seafloor between end members of rectangular, triangular and skewed distributions. Convection models show that significant fluctuations over longer periods (∼1 Gy) should exist, involving changes in ridge length and global tectonic reorganisations. Although independent, both convection models and kinematic reconstructions suggest that changes in ridge length are at least as significant as spreading rate fluctuations in driving changes in the seafloor area–age distribution through time.

Morphologic relationship between the cranial base and the mandible in patients with facial asymmetry and mandibular prognathism

This study was conducted to measure the dimensional changes in the cranial base and the mandible in patients with facial asymmetry and mandibular prognathism, and to examine the morphologic relationship between asymmetries of the cranial base and the mandible. The patients were 60 adults with mandibular prognathism, divided into a symmetry group (menton deviation, <2 mm; n = 30) and an asymmetry group (menton deviation, >4 mm; n = 30) according to the degree of menton deviation. Three-dimensional computed tomography scans were obtained with a spiral scanner. Landmarks were designated on the reconstructed 3-dimensional surface models. Linear, angular, and volumetric measurements of the cranial base and mandibular variables were made. In the asymmetry group, the hemi-base, anterior cranial base, and middle cranial base volumes were significantly larger (P <0.01), and crista galli to sphenoid, sphenoid to petrous ridge, anterior clinoid process to petrous ridge, and vomer to petrous ridge lengths were significantly longer (P <0.05) on the nondeviated side than on the deviated side. Menton deviation was significantly correlated with the difference in hemi-base volume, and ramal volume was significantly correlated with the difference in hemi-base and middle cranial base volumes between the nondeviated and deviated sides (P <0.05). In patients with facial asymmetry and mandibular prognathism, cranial base volume increased on the nondeviated side and was also correlated with mandibular asymmetry.

Seawater chemistry driven by supercontinent assembly, breakup, and dispersal

Global oceans are known to have alternated between aragonite and calcite seas. These oscillations refl ect changes in the Mg/Ca ratios of seawater that control biomineralization and the composition of marine carbonates, and are thought to be caused mainly by the time dependence of crustal accretion at mid-ocean ridge crests and the associated high-temperature mid-ocean ridge fl uid fl ux. Here we use global ocean basin reconstructions to demonstrate that the fl uctuations in hydrothermal ocean inputs are instead caused by the gradual growth and destruction of mid-ocean ridges and their relatively cool fl anks during long-term tectonic cycles, thus linking ocean chemistry to off-ridge low-temperature hydrothermal exchange. Early Jurassic aragonite seas were a consequence of supercontinent stability and a minimum in mid-ocean ridge length and global basalt alteration. The breakup of Pangea resulted in a gradual doubling in ridge length and a 50% increase in the ridge fl ank area, leading to an enhanced volume of basalt to be altered. The associated increase in the total global hydrothermal fl uid fl ux by as much as 65%, peaking at 120 Ma, led to lowered seawater Mg/Ca ratios and marine hypercalcifi cation from 140 to 35 Ma. A return to aragonite seas with preferential aragonite and high-Mg calcite precipitation was driven by pronounced continental dispersal, leading to progressive subduction of ridges and their fl anks along the Pacifi c rim.