Large Range Of Variation Research Articles

Patterns of morphological integration in the dental arches of individuals with malocclusion.

In humans, there is a large range of variation in the form of the maxillary and mandibular dental arches. This variation can manifest as either prognathism or retrognathism in either or both arches, which can cause malocclusion and lead to abnormal masticatory function. This study aims to identify aspects of variation and morphological integration existing in the dental arches of individuals with different types of malocclusion. Coordinate landmark data were collected along the gingival margins of 397 scanned dental casts and then analyzed using geometric morphometric techniques to explore arch form variation and patterns of morphological integration within each malocclusion type. Significant differences were identified between Class II forms (increased projection of upper arch relative to the lower arch) and Class III forms (lower arch projection beyond the upper arch) in symmetrical shape variation, including anteroposterior arch discrepancies and abnormal anterior arch divergence or convergence. Partial least squares analysis demonstrated that Class III dental arches have higher levels of covariance between upper and lower arches (RV = 0.91) compared to the dental arches of Class II (RV = 0.78) and Class I (RV = 0.73). These high levels of covariance, however, are on the lower end of the overall range of possible masticatory blocks, indicating weaker than expected levels of integration. This study provides evidence for patterns of variation in dental arch shape found in individuals with Class II and Class III malocclusions. Moreover, differences in integration found between malocclusion types have ramifications for how such conditions should be studied and treated. Am. J. Hum. Biol. 28:879-889, 2016. © 2016Wiley Periodicals, Inc.

Experimental determination of stable chlorine and bromine isotope fractionation during precipitation of salt from a saturated solution

In order to better understand the chlorine and bromine stable isotope fractionation that occurs when chloride and bromide salts precipitate from their saturated solutions, we determined experimentally the equilibrium fractionation factors between precipitating pure salt minerals and their coexisting saturated brine at 22°C. Fractionation factors (expressed as 103lnα(37Cl/35Cl)salt-brine and 103lnα81Br/79Brsalt-brine) obtained for 11 chloride and 7 bromide salts of geological and industrial interest show a relatively largerange of variation (from −0.31 to +0.41), with the salt that precipitates having either a lower or a higher isotope ratio than the brine from which they precipitate. A negative fractionation factor indicates that the brine has a larger isotope ratio than the precipitate, a positive factor that the precipitate has a larger isotope ratio. The results of the chlorine and bromine isotope fractionation measurements (103lnα) for the various salts at a temperature of 22±2°C are: LiCl: +0.03±0.05, NaCl: +0.35±0.08, KCl: −0.12±0.05, NH4Cl: +0.09±0.03, RbCl: −0.31±0.05, CsCl: −0.23±0.02, MgCl2: −0.02±0.02, CaCl2: +0.04±0.02, SrCl2: +0.15±0.02, BaCl2: +0.41±0.03, FeCl3: −0.23±0.05, LiBr: −0.03±0.09, NaBr: −0.07±0.05, KBr: 0.00±0.01, NH4Br: +0.11±0.05, MgBr2: +0.06±0.06, CaBr2: −0.06±0.04 and SrBr2: +0.05±0.06. In these measurements the uncertainty is defined as the 1σ standard deviation of replicate determinations. We compare the results to previous theoretical calculations based on reduced partition coefficients as well as with thermodynamic properties of precipitated salts. Though most of our experimental fractionation data qualitatively agree with theoretical predictions (e.g., larger isotope fractionation for Cl than for Br species), it remains difficult to directly and finely compare those estimations which is likely due to the complexness of the processes that take place in saturated solutions. We use the data to predict the δ37Cl evolution of the Earth's oceans' through geological time under the condition that solely isotope fractionation during evaporation and salt precipitation took place, together with erosion of evaporite deposits. Under these conditions, we calculate a δ37Cl decrease of at most 0.25‰ for the Earth's oceans during the last 1billion years. Such a trend is not observed in old evaporite deposits, in part because δ37Cl variations in most evaporite deposits are larger than the expected trend, and we conclude that δ37Cl may also be influenced by other processes such as chloride exchange with the deep Earth. We only observed very small bromine isotope fractionation during precipitation of bromide salts from brine. This small fractionation cannot explain the large deviation of δ81Br of dissolved evaporite samples from precipitation of seawater with a modern bromine isotope composition, and suggests large bromine isotope variations in the oceans through time.

A 20-year simulated climatology of global dust aerosol deposition

Based on a 20-year (1991–2010) simulation of dust aerosol deposition with the global climate model CAM5.1 (Community Atmosphere Model, version 5.1), the spatial and temporal variations of dust aerosol deposition were analyzed using climate statistical methods. The results indicated that the annual amount of global dust aerosol deposition was approximately 1161±31Mt, with a decreasing trend, and its interannual variation range of 2.70% over 1991–2010. The 20-year average ratio of global dust dry to wet depositions was 1.12, with interannual variation of 2.24%, showing the quantity of dry deposition of dust aerosol was greater than dust wet deposition. High dry deposition was centered over continental deserts and surrounding regions, while wet deposition was a dominant deposition process over the North Atlantic, North Pacific and northern Indian Ocean. Furthermore, both dry and wet deposition presented a zonal distribution. To examine the regional changes of dust aerosol deposition on land and sea areas, we chose the North Atlantic, Eurasia, northern Indian Ocean, North Pacific and Australia to analyze the interannual and seasonal variations of dust deposition and dry-to-wet deposition ratio. The deposition amounts of each region showed interannual fluctuations with the largest variation range at around 26.96% in the northern Indian Ocean area, followed by the North Pacific (16.47%), Australia (9.76%), North Atlantic (9.43%) and Eurasia (6.03%). The northern Indian Ocean also had the greatest amplitude of interannual variation in dry-to-wet deposition ratio, at 22.41%, followed by the North Atlantic (9.69%), Australia (6.82%), North Pacific (6.31%) and Eurasia (4.36%). Dust aerosol presented a seasonal cycle, with typically strong deposition in spring and summer and weak deposition in autumn and winter. The dust deposition over the northern Indian Ocean exhibited the greatest seasonal change range at about 118.00%, while the North Atlantic showed the lowest seasonal change at around 30.23%. The northern Indian Ocean had the greatest seasonal variation range of dry-to-wet deposition ratio, at around 74.57%, while Eurasia had the lowest, at around 12.14%.

Assessing filtration rates of exotic bivalves: dependence on algae concentration and seasonal factors

Due to their high filtration rates, exotic freshwater bivalves remove suspended organic matter from the water column, transferring resources to the sediment and increasing water clarity, which alters ecosystems. While there is a considerable amount of data on filtration rate of exotic bivalves, comparison between species is often invalid due to the utilization of different protocols for assessing filtration in experimental conditions. In this study, we quantified and compared for the first time the filtration rates of the zebra and quagga mussels and of two invasive Corbicula lineages (forms R and S) as a function of chlorophyll a concentration and season. The highest filtration rate observed was for the zebra mussel in fall and at high algal biomass. The incipient limiting level (ILL), defined as the chlorophyll a concentration at which the maximum filtration rate is observed, was observed in spring and summer in Corbicula species, and in summer and fall in Dreissena species. Overall, filtration rates presented a large range of variation, depending on chlorophyll a and season. Overall, Corbicula form S was observed as the best adapted to low food concentration. Moreover, Corbicula can switch to pedal feeding which gives them a competitive advantage at low chlorophyll a concentrations.

Adaptive digital fringe projection technique for high dynamic range three-dimensional shape measurement.

It is a challenge for any optical method to measure objects with a large range of reflectivity variation across the surface. Image saturation results in incorrect intensities in captured fringe pattern images, leading to phase and measurement errors. This paper presents a new adaptive digital fringe projection technique which avoids image saturation and has a high signal to noise ratio (SNR) in the three-dimensional (3-D) shape measurement of objects that has a large range of reflectivity variation across the surface. Compared to previous high dynamic range 3-D scan methods using many exposures and fringe pattern projections, which consumes a lot of time, the proposed technique uses only two preliminary steps of fringe pattern projection and image capture to generate the adapted fringe patterns, by adaptively adjusting the pixel-wise intensity of the projected fringe patterns based on the saturated pixels in the captured images of the surface being measured. For the bright regions due to high surface reflectivity and high illumination by the ambient light and surfaces interreflections, the projected intensity is reduced just to be low enough to avoid image saturation. Simultaneously, the maximum intensity of 255 is used for those dark regions with low surface reflectivity to maintain high SNR. Our experiments demonstrate that the proposed technique can achieve higher 3-D measurement accuracy across a surface with a large range of reflectivity variation.

Quantifying variation in human scalp hair fiber shape and pigmentation.

This study aims to evaluate the use of quantitative methods of measuring variation in scalp hair fiber shape and pigmentation and carry out exploratory data analysis on a limited sample of individuals from diverse populations in order to inform future avenues of research for the evolution of modern human hair variation. Cross-sectional area and shape and average curvature of scalp hair fibers were quantified using ImageJ. Pigmentation was analyzed using chemical methods estimating total melanin content through spectrophotometric methods, and eumelanin and pheomelanin content through HLPC analysis of melanin-specific degradation products. The initial results reinforced findings from earlier, traditional studies. African and African Diaspora scalp hair was significantly curled, (East) Asian hair was significantly thick, and European hair was significantly lighter in color. However, pigmentation analyses revealed a high level of variability in the melanin content of non-European populations and analysis of curvature found a large range of variation in the average curvature of East African individuals. Overall, these results suggest the usefulness of chemical methods for the elucidation of nonperceptible differences in scalp hair color and highlight the need for improvements in our assessment and understanding of hair fiber curvature. Am J Phys Anthropol 160:341-352, 2016. © 2016 Wiley Periodicals, Inc.

The High Mountain Asia glacier contribution to sea-level rise from 2000 to 2050

AbstractWe estimate all the individual glacier area and volume changes in High Mountain Asia (HMA) by 2050 based on Randolph Glacier Inventory (RGI) version 4.0, using different methods of assessing sensitivity to summer temperatures driven by a regional climate model and the IPCC A1B radiative forcing scenario. A large range of sea-level rise variation comes from varying equilibrium-line altitude (ELA) sensitivity to summer temperatures. This sensitivity and also the glacier mass-balance gradients with elevation have the largest coefficients of variability (amounting to ~50%) among factors examined. Prescribing ELA sensitivities from energy-balance models produces the highest sea-level rise (9.2 mm, or 0.76% of glacier volume a–1), while the ELA sensitivities estimated from summer temperatures at Chinese meteorological stations and also from 1°x1° gridded temperatures in the Berkeley Earth database produce 3.6 and 3.8 mm, respectively. Different choices of the initial ELA or summer precipitation lead to 15% uncertainties in modelled glacier volume loss. RGI version 4.0 produces 20% lower sea-level rise than version 2.0. More surface mass-balance observations, meteorological data from the glaciated areas, and detailed satellite altimetry data can provide better estimates of sea-level rise in the future.

Temporal Evolution of Spatial Computations for Visuomotor Control.

Goal-directed reaching movements are guided by visual feedback from both target and hand. The classical view is that the brain extracts information about target and hand positions from a visual scene, calculates a difference vector between them, and uses this estimate to control the movement. Here we show that during fast feedback control, this computation is not immediate, but evolves dynamically over time. Immediately after a change in the visual scene, the motor system generates independent responses to the errors in hand and target location. Only about 200 ms later, the changes in target and hand positions are combined appropriately in the response, slowly converging to the true difference vector. Therefore, our results provide evidence for the temporal evolution of spatial computations in the human visuomotor system, in which the accurate difference vector computation is first estimated by a fast approximation.

Electrical activity of ON and OFF retinal ganglion cells: a modelling study

Objective. Retinal ganglion cells (RGCs) demonstrate a large range of variation in their ionic channel properties and morphologies. Cell-specific properties are responsible for the unique way RGCs process synaptic inputs, as well as artificial electrical signals such as that from a visual prosthesis. A cell-specific computational modelling approach allows us to examine the functional significance of regional membrane channel expression and cell morphology. Approach. In this study, an existing RGC ionic model was extended by including a hyperpolarization activated non-selective cationic current as well as a T-type calcium current identified in recent experimental findings. Biophysically-defined model parameters were simultaneously optimized against multiple experimental recordings from ON and OFF RGCs. Main results. With well-defined cell-specific model parameters and the incorporation of detailed cell morphologies, these models were able to closely reconstruct and predict ON and OFF RGC response properties recorded experimentally. Significance. The resulting models were used to study the contribution of different ion channel properties and spatial structure of neurons to RGC activation. The techniques of this study are generally applicable to other excitable cell models, increasing the utility of theoretical models in accurately predicting the response of real biological neurons.

Strain- and temperature-induced effects in AlGaN/GaN high electron mobility transistors

This paper presents a physics-based model for computing the combined effect of applied strain and temperature on the device characteristics of aluminium gallium nitride (AlGaN/GaN) high electron mobility transistors (HEMTs). More specifically, the electrical response of the HEMT is predicted under applied biaxial strain from ±1% over a wide range of temperatures (300–500 K). In addition, the interface state densities at the Schottky-AlGaN interface are introduced in the model. This physics-based model calculates the charge due to applied, thermal and lattice mismatch strain and temperature effects at the two-dimensional electron gas (2DEG) interface of the HEMT. Coupled with a model for the 2DEG mobility that includes strain and temperature effects, current–voltage characteristics for the HEMT are derived above the threshold voltage. Regimes with large strain sensitivity and temperature compensation are identified and vice-versa. The analysis from the model clarifies the large range of strain response variations observed in the experimentally measured characteristics of HEMTs in literature. Furthermore, the developed model is a useful tool for predicting the response of HEMTs used in sensing and under the influence of packaging in extreme environments, especially when temperature fluctuation and strain coupling is of concern.

Prediction model of sulphur distribution ratio between CaO–FeO–Fe2O3–Al2O3–P2O5 slags and liquid iron over large variation range of oxygen potential during secondary refining process of molten steel based on ion and molecule coexistence theory

A thermodynamic model for predicting sulphur distribution ratio LS between CaO–FeO–Fe2O3–Al2O3–P2O5 slags and liquid iron, i.e. the ion and molecule coexistence theory (IMCT)–LS model, has been developed for slags in a large variation range of slag oxidisation ability based on the IMCT. The developed IMCT–LS model has been verified with measured data of oxygen, phosphorus and sulphur distribution equilibria between the slags and liquid iron from the literature. The results indicate that the desulphurisation reaction is mainly controlled by reaction (CaO)+[S] = (CaS)+[O] in the reducing zone with the optimised standard molar Gibbs free energy change of ; the desulphurisation reaction is dominated by reaction (FeO)+[S] = (FeS)+[O] in the oxidising zone with the reported standard molar Gibbs free energy change of . The influence of CaO on the desulphurisation ability of the slags can be counteracted by that of FetO because higher CaO content corresponds to lower FetO content in the slags. An asymmetric V type relationship between sulphur distribution ratio LS and the mass action concentration ratio or or or , or the mass percentage ratio (%FeO)/(%CaO) or (%Fe2O3)/(%CaO) or (%FetO)/(%CaO) or the simplified complex basicity or optical basicity can be established for the slags equilibrated with liquid iron in a temperature range from 1811 to 1927 K (1538 to 1654°C). The abovementioned mass action concentration ratios or mass percentage ratios of various iron oxides to basic oxide CaO can be recommended to represent the comprehensive effect of iron oxides FetO and basic oxide CaO on desulphurisation ability of the slags.

Demographic responses of boreal-montane orchid Malaxis monophyllos (L.) Sw. populations to contrasting environmental conditions

<p>In an age of changes in species’ geographical ranges, compounded by climatic and anthropogenic impacts, it become important to know which processes and factors influence plant populations and their persistence in the long term.</p><p>Here we investigated dynamic and fitness components in twelve populations of <em>Malaxis monophyllos</em> (L.) Sw., situated in different geographical (regions) and ecological (type of habitat) units. Although <em>M. monophyllos</em> is a rare species, characterized by highly fragmented, boreal-montane distribution range, in last few decades it successfully colonized secondary habitats in Polish uplands. Our results indicate that <em>M. monophyllos</em> is represented mainly by small populations, which annual spatial and temporal changes might be very high, what affects the ephemeral character of these populations, regardless of the region and type of habitat. This dynamic structure, in turn, is caused by intensive exchange of individuals in populations, as well as by their short above-ground life span. Despite the large range of variation in size and reproductive traits, we can distinguish some regional patterns, which indicate boreal region as the most optimal for <em>M. monophyllos</em> growth and persistence in the long term, and with montane and upland/anthropogenic populations, due to lower reproductive parameters, as the most threatened. Although it should be considered that anthropogenic populations, despite their lower reproductive parameters and instability in the long term, present an intermediate, geographical and ecological character, therefore they may be valuable in shaping, both <em>M. monophyllos</em>’ future range, as well as its potential for response on ongoing and future changes. In general, reproduction is the main factor differentiating of <em>M. monophyllos</em> populations in regions, and we can suspect that it may become the cause of the future differentiation and isolation of these populations, occurring with progressive range fragmentation.</p>

Next generation sequencing reveals disparate population frequencies among cytochrome P450 genes: clinical pharmacogenomics of the CYP2 family

85% of medications prescribed are metabolised by a CYP450 superfamily member. This family contains SNPs linked to medication response. 30,000 participants were evaluated to determine potential differences in ethnic distributions of nucleotide polymorphisms. Next generation sequencing with the Ion Torrent PGM was used to genotype medication response genes. Variations in these key enzymes were common leading to a variety of responses to medication therapy. Our study showed there exists a large range of genetic variation within/between various ethnic groups. With exception of CYP2C9, the wild type genotype is not most common. Each gene showed a unique pattern of distribution that significantly differed within and across ethnic groups. These findings call into question the concept of a 'normal' patient. Our results highlight the need for and applicability of pharmacogenomic testing. Genetic determination of patient response groups can help tailor therapies and increase the likelihood of success.

Takagi-Sugeno Model-based Steering Control for Autonomous Vehicles with Actuator Saturation

This paper is devoted to the development of a novel control law for an autonomous vehicle. The control goal is to perform lane keeping under multiple constraints, namely actuator saturation of the steering system, roads with unknown curvature, and uncertain lateral wind force. Such system constraints will be explicitly considered in the control design procedure. To achieve this goal, we propose a novel constrained Takagi-Sugeno control method using non-quadratic Lyapunov stability framework. The obtained non-parallel distributed compensation controller is not only able to handle various system constraints but also a large variation range of vehicle speed. Especially, by means of the well-known Taylor’s approximation method we can significantly reduce the numerical complexity of the proposed control method to ease the real-time control implementation. The control synthesis conditions are expressed in terms of linear matrix inequalities which can be efficiently solved with available solvers. The effectiveness of the proposed method is demonstrated with different simulation scenarios.

Petrology and geochemistry of the Guyang hornblendite complex in the Yinshan block, North China Craton: Implications for the melting of subduction-modified mantle

The hornblendite complexes hosted in the Guyang granite-greenstone terrane form part of the Neoarchean basement in the Western Block of the North China Craton. In this study, we focus on the largest one from this block, previously named the Guyang komatiite, and present results from lithological, geochronological and geochemical studies. The dominant lithology in the Guyang hornblendite complex is greenschist facies hornblendite, and can be divided into clinopyroxene hornblendite (∼75%) and olivine-orthopyroxene hornblendite (∼25%). The oldest calculated Re depletion model ages (TRD) of these hornblendites is of 2454Ma, and the zircon U-Pb age of the wallrock is 2480Ma, with single-stage depleted mantle Nd model ages TDM1(Nd) varying from 2.61 to 2.88Ga. These data suggest that the Guyang hornblendite complexes formed during Neoarchean-Paleoproterozoic time. The hornblendites show low SiO2, high MgO contents and are enriched in Cr, Ni, and LREE with negative Ce anomalies and depleted in Ti, Nb and Ta. Their 187Os/188Os ratios range from 0.11145 to 0.11279, with γOs(2.5Ga) varying from −3.9 to +1.4. Geochemically, the olivine-orthopyroxene hornblendite shows little variation with typical cumulate feature. In contrast, the clinopyroxene hornblendite shows a large range of chemical variation. In the CaO vs. MgO and CaO/Al2O3 vs. MgO diagrams, the clinopyroxene hornblendite shows Opx fractionation trend. Combined with lithological information, we infer that the hornblendite magma was emplaced as a crystal mush, with orthopyroxene as cumulus phase. The Os and Nd isotope composition, negative Nb, Ta, Ce anomalies, and the relationships in Th/Yb–Nb/Yb diagram suggest that the Guyang hornblendites formed from a source mantle that was modified by subduction-related melts/fluids derived from a seawater-altered basaltic slab. Compared with typical Archean komatiites, the rocks of present study show significant differences in lithological and geochemical characteristics, and thus it cannot be named as komatiite. To explain these characteristics, we propose a geodynamic model involving ridge subduction and slab window mechanism to account for the formation of the Guyang hornblendite complex.

Evaluating color texture descriptors under large variations of controlled lighting conditions.

The recognition of color texture under varying lighting conditions remains an open issue. Several features have been proposed for this purpose, ranging from traditional statistical descriptors to features extracted with neural networks. Still, it is not completely clear under what circumstances a feature performs better than others. In this paper, we report an extensive comparison of old and new texture features, with and without a color normalization step, with a particular focus on how these features are affected by small and large variations in the lighting conditions. The evaluation is performed on a new texture database, which includes 68 samples of raw food acquired under 46 conditions that present single and combined variations of light color, direction, and intensity. The database allows us to systematically investigate the robustness of texture descriptors across large variations of imaging conditions.

Sub-Poissonian photon emission in coupled double quantum dots–cavity system**Project supported by the National Natural Science Foundation of China (Grant Nos. 61372037 and 61401035), the Beijing Excellent Ph.D. Thesis Guidance Foundation, China (Grant No. 20131001301), and the Fund of State Key Laboratory of Information Photonics and Optical Communications (Beijing University of Posts and Telecommunications), China (Grant No. IPOC2015ZC05).

In this work, we theoretically analyze the few-photon emissions generated in a coupled double quantum dots (CDQDs)-single mode microcavity system, under continuous wave and pulse excitation. Compared with the uncoupled case, strong sub-Poissonian character is achieved in a CDQDs–cavity system at a certain laser frequency. Based on the proposed scheme, single photon generation can be obtained separately under QD–cavity resonant condition and off-resonant condition. For different cavity decay rates, we reveal that laser frequency detunings of minimum second-order autocorrelation function are discrete and can be divided into three regions. Moreover, the non-ideal situation where two QDs are not identical is discussed, indicating the robustness of the proposed scheme, which possesses sub-Poissonian character in a large QD difference variation range.

Stable single-photon detection based on Si-avalanche photodiode in a large temperature variation range

In this paper, we present a stable single-photon detection method based on Si-avalanche photodiode (Si-APD) operating in Geiger mode with a large temperature variation range. By accurate temperature sensing and direct current (DC) bias voltage compensation, the single-photon detector can work stably in Geiger mode from −40 °C to 35 °C with an almost constant avalanche gain. It provides a solution for single-photon detection at outdoor operation in all-weather conditions.

Delay-dependent LMI-based robust stability criterion for discrete and distributed time-delays Markovian jumping reaction–diffusion CGNNs under Neumann boundary value

In this paper, variational methods, Lyapunov stability theory, Homomorphic mapping theory, M-matrix, H-matrix and linear matrix equality (LMI) technique are synthetically employed to obtain the LMI-based stochastically exponential robust stability criterion for a discrete and distributed time-delays Markovian jumping reaction–diffusion Cohen–Grossberg neural networks (CGNNs) with uncertain parameters. It is worth mentioning that the methods employed in this paper improve those of previous related literature to some extent, and the obtained stability criterion can be easily and efficiently computed by computer LMI toolbox. Moreover, a numerical example is presented to illustrate the effectiveness of the proposed methods thanks to the large allowable variation range of time-delays.

Postwall Slotline and Its Application in Design of Short-Pulse Tapered Slot Antennas

A postwall slotline (PWS), composed of a bilateral slotline and two metalized via arrays aligned at the slot edges, is proposed and its application in the design of short-pulse tapered slot antennas (TSAs) is investigated. The characteristic impedance of the PWS is derived by a partly analytical and partly empirical method. Compared with the conventional slotline, the PWS has lower available characteristic impedance and larger variation range, which is favorable for meeting diverse design specifications. The PWS is employed in the design of two TSAs with exponential profile and Gaussian profile, respectively. The two tapered PWS antennas are fabricated and their performance in both frequency domain and time domain is investigated. The results show that the TSA based on the PWS is featured by broad bandwidth, low cross-polarization, and good suitability for short-pulse applications.