Shape Components Research Articles

Low resolution scans can provide a sufficiently accurate, cost- and time-effective alternative to high resolution scans for 3D shape analyses.

BackgroundAdvances in 3D shape capture technology have made powerful shape analyses, such as geometric morphometrics, more feasible. While the highly accurate micro-computed tomography (µCT) scanners have been the “gold standard,” recent improvements in 3D surface scanners may make this technology a faster, portable, and cost-effective alternative. Several studies have already compared the two devices but all use relatively large specimens such as human crania. Here we perform shape analyses on Australia’s smallest rodent to test whether a 3D scanner produces similar results to a µCT scanner.MethodsWe captured 19 delicate mouse (Pseudomys delicatulus) crania with a µCT scanner and a 3D scanner for geometric morphometrics. We ran multiple Procrustes ANOVAs to test how variation due to scan device compared to other sources such as biologically relevant variation and operator error. We quantified operator error as levels of variation and repeatability. Further, we tested if the two devices performed differently at classifying individuals based on sexual dimorphism. Finally, we inspected scatterplots of principal component analysis (PCA) scores for non-random patterns.ResultsIn all Procrustes ANOVAs, regardless of factors included, differences between individuals contributed the most to total variation. The PCA plots reflect this in how the individuals are dispersed. Including only the symmetric component of shape increased the biological signal relative to variation due to device and due to error. 3D scans showed a higher level of operator error as evidenced by a greater spread of their replicates on the PCA, a higher level of multivariate variation, and a lower repeatability score. However, the 3D scan and µCT scan datasets performed identically in classifying individuals based on intra-specific patterns of sexual dimorphism.DiscussionCompared to µCT scans, we find that even low resolution 3D scans of very small specimens are sufficiently accurate to classify intra-specific differences. We also make three recommendations for best use of low resolution data. First, we recommend that extreme caution should be taken when analyzing the asymmetric component of shape variation. Second, using 3D scans generates more random error due to increased landmarking difficulty, therefore users should be conservative in landmark choice and avoid multiple operators. Third, using 3D scans introduces a source of systematic error relative to µCT scans, therefore we recommend not combining them when possible, especially in studies expecting little biological variation. Our findings support increased use of low resolution 3D scans for most morphological studies; they are likely also applicable to low resolution scans of large specimens made in a medical CT scanner. As most vertebrates are relatively small, we anticipate our results will bolster more researchers in designing affordable large scale studies on small specimens with 3D surface scanners.

Influence of the low local symmetry of Er3+ ions on magnetic circular dichroism and absorption spectra of f-f transitions in ErFe3(BO3)4 single crystal

Linearly polarized absorption spectra and magnetic circular dichroism (MCD) spectra of ErFe3(BO3)4 single crystal were measured in the range of 9000–23000 cm−1 at 90 K. The absorption spectra of f-f transitions were decomposed into the Lorentz shape components and intensities of the components were found. MCD spectra permitted us to measure the Zeeman splitting of some transitions and so to determine changes of the Landé factor along the C3 axis of the crystal during these transitions. Optical and magneto-optical properties of f-f transitions in the ErFe3(BO3)4 crystal were compared with those in the ErAl3(BO3)4 crystal. Substantial difference of the properties connected with the difference of the Er3+ ions local symmetry in two crystals was revealed. Large splitting of one of the f-f transitions without magnetic field, which is not possible for the Kramers doublets, was observed. It was explained by appearance of two absorbing centers due to the local decrease of symmetry in the excited state. Appreciable difference of the local vibrations energy in some excited states was revealed.

Laboratory for Drawingless Manufacturing

Abstract To achieve quick response of production, it is necessary to abandon the traditional form of production process planning. Nowadays, most of the products are designed by using CAx software. The product design 3D model contains not only the geometrical data of product, but may contain a part of the process plan and technological data as well. The process plan is important to enter the process of manufacturing of various precision engineering components of complex shape. Using the highest level of programming through graphical engineering system, a 3D model and the ISO programs using CNC machine tools were designed.

Disentangling representations of shape and action components in the tool network

Shape and how they should be used are two key components of our knowledge about tools. Viewing tools preferentially activated a frontoparietal and occipitotemporal network, with dorsal regions implicated in computation of tool-related actions and ventral areas in shape representation. As shape and manners of manipulation are highly correlated for daily tools, whether they are independently represented in different regions remains inconclusive. In the current study, we collected fMRI data when participants viewed blocks of pictures of four daily tools (i.e., paintbrush, corkscrew, screwdriver, razor) where shape and action (manner of manipulation for functional use) were orthogonally manipulated, to tease apart these two dimensions. Behavioral similarity judgments tapping on object shape and finer aspects of actions (i.e., manners of motion, magnitude of arm movement, configuration of hand) were also collected to further disentangle the representation of object shape and different action components. Information analysis and representational similarity analysis were conducted on regional neural activation patterns of the tool-preferring network. In both analyses, the bilateral lateral occipitotemporal cortex showed robust shape representations but could not effectively distinguish between tool-use actions. The frontal and precentral regions represented kinematic action components, whereas the left parietal region (in information analyses) exhibited coding of both shape and tool-use action. By teasing apart shape and action components, we found both dissociation and association of them within the tool network. Taken together, our study disentangles representations for object shape from finer tool-use action components in the tool network, revealing the potential dissociable roles different tool-preferring regions play in tool processing.

Evolution of jaw disparity in fishes

AbstractThe morphology of the vertebrate lower jaw has been used to infer feeding ecology, with transformations in mandibular shape and structure likely to have facilitated the emergence of different feeding behaviours in vertebrate evolution. Here we present elliptical Fourier shape and principal component analyses, characterizing and comparing the disparity of jaw shape in early gnathostomes and their modern primitively aquatic counterparts. 83% of shape variation is summarized on the first three principal component axes and all component clades of early gnathostomes exhibit overlapping morphological variation. Non‐tetrapodomorph Palaeozoic sarcopterygians are more disparate than their extant counterparts whereas extant chondrichthyans are more disparate than their Palaeozoic counterparts. More generally, extant jawed fishes are more disparate than their Palaeozoic relatives largely because of the extensive shape variation exhibited by mandibles of extant actinopterygians. Only some areas of shape space vacated by Palaeozoic gnathostomes have been convergently refilled by living taxa. Characterization of theoretical jaw morphologies demonstrates that fewer than half of all possible shapes are realized by the jawed fishes that comprise our empirical dataset; many of these morphologies are realized by unrepresented terrestrial tetrapods, implying environmental constraint. Our results are incompatible with the early burst model of clade evolution and contradict the hypothesis that maximum disparity is reached early in the evolutionary history of jawed fishes.

Unsteady free surface flow above a moving circular cylinder

A problem on non-stationary free surface flow of infinitely deep ideal fluid generated by the motion of a submerged body is considered. The water wave problem is reduced to the integral–differential system of equations for the functions defining free surface shape, normal, and tangential velocity components on the free boundary. Small-time asymptotic solution is constructed for the case of circular cylinder that moves with constant acceleration from rest. The role of non-linearity is clarified by analysis of this approximate solution which describes the formation of added mass layers, splash jets, and finite amplitude surface waves.

Effects of dietary intake patterns from 1 to 4\xa0years on BMI z-score and body shape at age of 6 years: a prospective birth cohort study from Brazil

PurposeTo assess the association between dietary intake patterns from 1 to 4 years and BMI and body shape at age of 6 years.MethodsThis longitudinal study was based on 3374 Brazilian children from the 2004 Pelotas Birth Cohort Study. We used previously described dietary patterns from 1 to 4 years as the main exposure. We defined body shape using scores for corpulence (a recently described body shape component measured by Photonic Scanner), and trunk and gynoid fat mass percentage from DXA. We run linear regression models to evaluate the associations between dietary patterns from 1 to 4 years and BMI and body shape at 6 years.ResultsSeveral apparent associations between dietary patterns and BMI or body shape were explained by sociodemographic factors. High adherence to snacks (positive loadings to coffee, bread and cookies) at 4 years predicted lower BMI, but higher gynoid fat mass percentage at 6 years, while higher adherence to staple at 2 years (positive loadings to rice and beans) predicted higher trunk fat mass and lower gynoid fat mass. Finally, higher scores on milks at 1 year (positive loading to breast milk) predicted higher gynoid fat mass at 6 years.ConclusionThere were inconsistent associations between dietary patterns in infancy and early childhood and BMI and body shape at 6 years. In adjusted analyses, higher adherence to breast milk at 1 year and to snacks at 4 years appeared to be beneficial for body shape, associated with lower BMI, but higher peripheral fat.

Lubricant Influence on the Ejection and Roughness of In-Die Electro Sinter Forged Ti-Discs

Electro Sinter Forging (ESF) is a new sintering process based on Joule heating by high electrical current flowing through compacted metal powder under mechanical pressure. The whole process takes about three seconds and is based on a closed-die setup, where the sample is sintered inside a die. A near-net shape component is therefore manufactured. One of the challenges associated with this process is the ejection of the sample after sintering. Due to powder compaction and axial loading during sintering, a radial pressure is generated at the die/sample interface. Consequently, the ejection can be difficult, and the final quality of the sintered component in terms of roughness and surface defects may be affected. In the present work, four different lubricants and non-lubricated conditions were tested to investigate the effects on the final part quality. The sintered sample is a disc made of commercially pure titanium powder. The force was measured while ejecting the samples by using a speed-controlled press. The surface roughness parameter Sa was measured by using a laser confocal microscope.

Technical Note: An approach to building a Monte Carlo simulation model for a double scattering proton beam system.

The purpose of this study was to demonstrate and develop a Monte Carlo (MC) simulation model for a passive double scattering compact proton therapy system based on limited information of the mechanical components. We built a virtual machine source model (VMSM) which included a detailed definition of each beam-modifying component in the nozzle. Conceptually, it is similar to the conventional virtual analytical source model (VASM), except that the numerical machine nozzle or beamline is constructed in the VMSM, whereas in the VASM analytical parameters characterizing the energy spectrum and source fluence distribution are sought. All major beam shaping components were included in the VMSM and the model simulates interactions of the beam with a rotating range modulation wheel (RMW) combined with the beam current modulation. The RMWs, the first and second scatterer in the system were generated and tuned to reproduce measurement data as closely as possible. To validate the model, we compared the percent depth dose curves, spread out Bragg peaks (SOBPs) and lateral profiles against measured commissioning beam data. The agreement of beam range between the MC calculation and measurement was within 1 mm for all beam options. The distal-falloff length was in good agreement as well (<1 mm for the large and deep groups, <1.5 mm for the small group). Agreement to within 2.5 mm of measured SOBP widths was obtained for all MC calculations. For lateral profiles, differences were found to be less than 2 mm. We demonstrated that with limited geometrical information it is possible to build an acceptable source model for MC simulations of a passive double scattering compact proton therapy system. The agreement between the measurements and the MC model provides validation for use of the model for further studies of the dosimetric effects in patient treatments.

Roll formability of aluminium foam sandwich panels

An aluminium foam sandwich (AFS) material was formed by V-die bending and roll forming. The V-bent sections showed material failure by shear fracture of the aluminium foam core and by delamination at the core-cover sheet interface. This led to a high-gull wing defect and a limited section depth that could be formed. In contrast, the roll forming process allowed the manufacture of long sections with acceptable profile depth. Only minor gull wing was observed, and this was related to a low-shear deformation of the aluminium foam core and an intact adhesion at the core-cover sheet interface. The higher material formability observed in roll forming compared to that in V-die bending was attributed to a more evenly distributed contact pressure and more homogeneous forming, due to the incremental nature of the process, combined with a continuous contact of the metal sheet with the top and bottom rolls. Some forming problems were also observed in the roll-formed AFS components, but overall, the results of this study suggest that roll forming represents a good alternative to bending or stamping for the forming of longitudinal components of simple cross section shape that are of interest to the transport, solar or housing industries.

A response spectrum-based indicator for structural damage prediction

Improving predictive relationships between strong ground motion and seismically induced damage in buildings is an important topic for seismic risk assessment. Spectral acceleration at a structure’s fundamental period Sa(T1) has often been used as the indicator of the potential damage a given ground motion may induce on structural systems. However, such a scalar indicator (Damage Potential Indicator, DPI) captures only limited information about the ground motion time history and response spectrum shape. In a severely damaged state, the effective period of a structure will change, which makes the structure respond to other parts of the response spectrum. In this study, a new response spectrum-based DPI that contains an intensity component and a spectral shape component is proposed. The critical period range of the response spectrum that should be considered in spectral shape evaluation is determined using a circle rule for bilinear single-degree-of-freedom (SDOF) systems. The effectiveness of the newly proposed DPI is validated by comparing damage potential similarity using a database of ground motion records.

A miniaturized meandered printed monopole antenna for triband applications

AbstractThis work presents the design of a miniaturized, low profile tri‐band printed monopole antenna for WLAN and WiMAX applications. The proposed design comprises of a meandered shape component, an inverted G shape component and a defected ground plane to achieve resonance in any 3 bands. A prototype has been designed and fabricated based on the proposed structure. The antenna has a compact size of 0.18 λ × 0.15 λ, that is, 23 × 20 mm2. The measured results show that the antenna is operating in 3 bands, that is, 2.39–2.52 GHz, 3.3–4.47 GHz, and 5.15–6.0 GHz which covers both the WLAN 2.4/5.2/5.8 GHz bands and WiMAX 3.5/5.5 GHz bands. These results are in good agreement with the simulations outcomes and exhibit that the antenna is capable of obtaining 3 distinct bands with its compact size.

Longitudinal Changes in Facial and Basicranial Integration in the Mediolateral Axis

ObjectivesMany studies over the past decade have employed morphological integration as a framework for understanding the interaction of the facial and basicranial skeleton in humans, the great apes, and our fossil lineage. Fewer studies, however, have examined morphological integration in the facial and basicranial portions of the skull in a true longitudinal sample. Most of these longitudinal studies have focused primarily on lateral cephalograms. While useful, these datasets only examine shape and morphological integration from the lateral aspect, limiting the types of questions that can be explored, primarily in the mediolateral axis. To rectify this gap in the data, we set out to study aspects of both symmetric and asymmetric shape variation in a longitudinal postero‐anterior (PA) celphalometric dataset in order to ascertain how patterns of morphological integration change in the mediolateral plane as a function of growth.MethodsPA cephalograms from a total of 55 individuals from the longitudinal Iowa Facial Growth Study were digitized using 13 coordinate landmarks across the mandible, face, and cranial base to capture patterns of integration and modularity. This data was collected at three time points per patient: age 4, age 11, and in adulthood. Data were submitted to MorphoJ for a Two‐Block Partial Least Squares (2‐B PLS) analysis of both the symmetric and asymmetric shape components in order to examine morphological integration between the face and cranial base.Results2‐B PLS results for the symmetric shape component show that integration between the face and cranial base decrease (becoming more modularized) from age 4 (RV=0.41, p&lt;0.001), to age 11 (RV=0.25, p&lt;0.001) before increasing again at the adult time point (RV=0.35, p&lt;0.001). For the asymmetric component, however, levels of integration between the face and basicranium decrease consistently from age 4 (RV=0.59, p&lt;0.001) to adult (RV=0.47, p&lt;0.001). These results indicate that while levels of cranial integration tend to decrease throughout growth, this decrease is only consistent in the asymmetric shape component, potentially indicating that modularity of the face and cranial base has a strong mediolateral (side‐to‐side) component.ConclusionThese results show that while overall trajectories of facial/cranial base integration show a similar trend toward modularity as individuals grow, this pattern of modularity is only a linear when examining the asymmetric shape component. This aspect of shape has been largely overlooked in the integration literature to date and warrants further study.This abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.

The relationship between two different measures of osteoarthritis bone pathology, bone marrow lesions and 3D bone shape: data from the osteoarthritis initiative

Purpose: Magnetic resonance imaging (MRI) has provided great insights into the development of OA, and helped highlight the importance of subchondral bone pathology. Bone shape and bone marrow lesions (BMLs) represent different features of MRI-detected subchondral pathology in osteoarthritis (OA) and while BMLs are well studied the relationship between these two remains poorly understood. It is important to understand if they represent a single construct or different parts of the OA process, and to further explore their use as imaging biomarkers. The aim of this study was to determine how these features are related and how they change in OA progression. Methods: 600 participants from the FNIH Biomarkers Initiative of the OAI were included, having Kellgren–Lawrence (KL) 1, 2 or 3 at baseline and MRI data at baseline and 24 months. MRI images obtained from the OAI were scored for BMLs using the semi-quantitative MOAKS system that scores 3 features using an ordinal scale for size, number of BMLs and percentage of lesion that is a BML as opposed to a cyst. Quantitative 3D bone shape data was provided by Imorphics (Manchester, UK) using active appearance models (AAMs) applied separately for femur and tibia from 3T DESS-we images. The shape vector for each bone was calculated by taking the principal components of the mean non-OA shape and the mean OA shape and the vector was normalised by setting the mean OA shape to +1 and mean non-OA shape as −1, with each unit increase of 1 representing 1 standard deviation (SD) calculated in non-OA knees. Four BML scores were computed: “BML total size”, “BML total number”, “BML total sub regions” and BML maximum size”. At baseline the correlation between the BML scores and bone shape measures were assessed using Spearman`s correlation coefficients. The association between 3D quantitative bone shape vectors and BMLs at baseline was analysed using linear regression. Presence of a BML was defined as BML total size ≥ 1. Responsiveness was calculated for both features in 4 pre-defined progression groups and reported as standardised response means (SRMs).Due to nesting of repeated measurements within individuals, multilevel linear modelling was used to assess the longitudinal relationship between change in BML size and change in bone shape vector. Results: Mean age was 61.5, 59% were female and mean BMI was 30.7. Correlation between baseline femur shape vector and femur BML total size was r = 0.28, P < 0.001 and similar for the tibia. Linear models revealed an association between presence of a femur BML at baseline and baseline 3D femur vector in both univariable and multivariable models (adjusted coefficient 0.49, 95% CI 0.30, 0.68) indicating a more positive femur vector (indicative of “increased OA”) in individuals with BMLs at baseline, with a difference equivalent to 0.5 × SD of non-OA knees. Longitudinally bone shape demonstrated more responsiveness to change than all BML measures (SRM 0.89 vs 0.13) for femur bone shape vector vs BML total size respectively (Table 1). Univariable growth models revealed that bone shape vector tended to be more positive over time (indicating worsening) while BML total size reduced over time. Multilevel models also showed that an increase in BML size was related to a more positive bone shape vector (representing worsening OA). Conclusions: There is a relationship between bone shape and BMLs, with increasing OA bone shape vector associated with higher prevalence of BMLs. Bone shape vector demonstrated greater responsiveness than semi-quantitative BMLs over time periods typical of a clinical trial.Table 1Responsiveness of bone shape and BML measures over 24 monthsRadiographic and pain progression N = 194Radiographic progression only N = 103Pain progression only N = 103No progression N = 2002 year responsiveness, SRM (95%CI)Bone shapeFemur0.89 (0.72,1.02)1.02 (0.85,1.20)0.46 (0.31,0.61)0.61 (0.49,0.72)Tibia0.84 (0.70,0.97)0.76 (0.56,0.96)0.26 (0.07,0.43)0.47 (0.33,0.69)BMLsFemur BML total size−0.13 (−0.26,0.02)−0.15 (−0.35,0.07)−0.31 (−0.51,−0.13)−0.24 (−0.37,0.13)Femur BML total number0.38 (0.26,0.50)0.20 (−0.02,0.41)0.17 (−0.04,0.35)0.27 (0.14,0.38)Tibia BML total size0.11 (−0.02,0.26)0.14 (−0.04,0.31)−0.04 (−0.23,0.15)−0.01(−0.16,0.11)Tibia BML total number0.37 (0.24,0.51)0.31 (0.12,0.51)0.19 (0.00,0.33)0.16 (0.02,0.29)Femur BML maximum size−0.05 (−0.19,−0.09)−0.01 (−0.19,0.21)−0.20 (−0.38,0.01)−0.11 (−0.25,0.02)BML total sub regions−0.02 (−0.15,0.13)−0.03 (−0.23,0.15)−0.13 (−0.32,0.07)−0.06 (−0.20,0.08) Open table in a new tab

Genome-wide determinants of sequence-specific DNA binding of general regulatory factors.

General regulatory factors (GRFs), such as Reb1, Abf1, Rap1, Mcm1, and Cbf1, positionally organize yeast chromatin through interactions with a core consensus DNA sequence. It is assumed that sequence recognition via direct base readout suffices for specificity and that spurious nonfunctional sites are rendered inaccessible by chromatin. We tested these assumptions through genome-wide mapping of GRFs in vivo and in purified biochemical systems at near–base pair (bp) resolution using several ChIP-exo–based assays. We find that computationally predicted DNA shape features (e.g., minor groove width, helix twist, base roll, and propeller twist) that are not defined by a unique consensus sequence are embedded in the nonunique portions of GRF motifs and contribute critically to sequence-specific binding. This dual source specificity occurs at GRF sites in promoter regions where chromatin organization starts. Outside of promoter regions, strong consensus sites lack the shape component and consequently lack an intrinsic ability to bind cognate GRFs, without regard to influences from chromatin. However, sites having a weak consensus and low intrinsic affinity do exist in these regions but are rendered inaccessible in a chromatin environment. Thus, GRF site-specificity is achieved through integration of favorable DNA sequence and shape readouts in promoter regions and by chromatin-based exclusion from fortuitous weak sites within gene bodies. This study further revealed a severe G/C nucleotide cross-linking selectivity inherent in all formaldehyde-based ChIP assays, which includes ChIP-seq. However, for most tested proteins, G/C selectivity did not appreciably affect binding site detection, although it does place limits on the quantitativeness of occupancy levels.

Extracting the Principal Shape Components via Convex Programming.

We present a general method for extracting a region from an image (or 3D object) that can be expressed, or approximated, by taking unions and set differences from a collection of template shapes in a dictionary. We build on recent work that shows how this geometric problem can be recast in the language of linear algebra, with set operations on shapes translated into linear combinations of vectors, and solved using convex programming. This paper presents a set of sufficient conditions for which this convex program returns the "correct" shape. These conditions are robust in that they can account for the shapes that have indistinct boundaries, or model mismatch between the shapes in the dictionary and the target region in the image. We also present two different methods for solving the convex extraction program. The first method simply recasts the problem as a linear program, while the second uses the alternating direction method of multipliers with a series of easily computed proximal operators. We present a number of numerical experiments that use the framework to perform image segmentation, optical character recognition, and find multi-resolution geometrical descriptions of 3D objects.

Development of a rolling finishing system to deliver net shape components from titanium structural extruded shapes

The high cost of manufacturing with titanium is the predominant barrier to wider adoption of the material into new applications, despite attractive material properties. The manufacture of long structural shaped product for framing applications has largely been relegated to lower cost alternative materials. Producing comparable structures from titanium requires different manufacturing processes due to the material’s response during thermo-mechanical deformation. Traditional bulk rolling of titanium into shapes has proven enigmatic due to the occurrence of shear banding and cracking from significant levels of non-uniform deformation and sensitivities to temperature non-uniformities. The current manufacturing method of long structural shapes is through an extrusion process. The inability to deliver thickness and surface quality dictate the machining of all surfaces to deliver complete components. This machining operation is the most significant cost driver for the components due to material loss and difficulty of machining titanium. This experimental effort proved a novel system, for the processing of titanium, that couples the two processes to deliver capabilities that neither could independently. The coupling of these two systems enabled mitigations of shortcomings of the individual systems. Thicknesses and surface quality aligned with a finished or net shape component were achieved without requiring a machining operation. In the experimental effort, a series of specimen were processed under varying temperature and deformation rates during rolling. These process variables are correlated to resulting material quality and to complexities associated with the coupling of the rolling and extrusion operations.

Disconnectedness: A new moment invariant for multi-component shapes

In this paper we further develop the recent concept of multi-component shapes, which is applicable to image processing and image analysis tasks. The domain of multi-component shapes is very diverse and includes shapes that correspond to a group of objects that act together (e.g. a fish shoal), natural components of a segmented object (e.g. cells in embryonic tissues), a set of shapes corresponding to the same object appearing at different times (e.g. human gait in an image sequence), and many more.So far, there are few methods for numerically evaluating multi-component shapes. In this paper we introduce one such method: a disconnectedness measure, that naturally corresponds to multi-component shapes, and has no analogue in single-component shape measures. The new measure depends on the number of shape components, the whole shape but also the shape of its components, on the relative size of the shape’s components and their mutual position. All these are natural requirements for a “disconnectedness” multi-component shape measure. In addition, the new measure is invariant with respect to translation, rotation and scaling transformations. The measure is simple and fast to compute.The disconnectedness measure introduced here is a generic image analysis tool. It has not been developed for a specific application. As such, it can be applied to a variety of applications. Several of them are provided in the paper, as well as synthetic examples that support a better understanding of the behavior of the new measure.

Multilocus phylogeny, divergence times, and a major role for the benthic-to-pelagic axis in the diversification of grunts (Haemulidae)

We present a phylogenetic analysis with divergence time estimates, and an ecomorphological assessment of the role of the benthic-to-pelagic axis of diversification in the history of haemulid fishes. Phylogenetic analyses were performed on 97 grunt species based on sequence data collected from seven loci. Divergence time estimation indicates that Haemulidae originated during the mid Eocene (54.7–42.3 Ma) but that the major lineages were formed during the mid-Oligocene 30–25 Ma. We propose a new classification that reflects the phylogenetic history of grunts. Overall the pattern of morphological and functional diversification in grunts appears to be strongly linked with feeding ecology. Feeding traits and the first principal component of body shape strongly separate species that feed in benthic and pelagic habitats. The benthic-to-pelagic axis has been the major axis of ecomorphological diversification in this important group of tropical shoreline fishes, with about 13 transitions between feeding habitats that have had major consequences for head and body morphology.

A Comprehensive Review on Wire Electrical Discharge Based Hybrid Turning (WEDHT)

Conventional machining of electrically conductive high hardness materials poses challenging issues in machine tool industry. This gave rise to the development of hybrid non – conventional machining processes. Wire electrical discharge hybrid turning (WEDHT) is a novel hybrid process for both macro and micro level cylindrical components of complicated shape and size. WEDHT combines wire electrical discharge machining (WEDM) and turning operation as single operation. The WEDHT process is influenced by the many input parameters like discharge voltage, discharge current, pulse-on time, pulse-off time, spark gap and non-electrical parameters such as type of dielectrics, flushing pressure, workpiece rotational speed, wire feed etc. Hence the selection of best parameter levels in WEDHT is a complex and challenging decision without complete process understanding. This review article focused on detailed study of parametric effects on material removal rate, surface finish, roundness, recast layer and crater formation are carried out. Finally, the future directions of WEDT hybrid process is highlighted.