Spherical Head Research Articles

A statistical comparison of the spatial distribution of ASSR sources across age

Event Abstract Back to Event A statistical comparison of the spatial distribution of ASSR sources across age Ehsan Darestani Farahani1*, Jan Wouters1 and Astrid Van Wieringen1 1 KU Leuven, Department of Neurosciences, Belgium Changes in auditory temporal processing may affect speech perception in ageing persons. Temporal processing is mediated by stimuli-induced synchronized activity in the central auditory system. The auditory steady-state response (ASSR) is a non-invasive measure of synchronized neural activity, induced by amplitude modulated (AM) acoustic stimuli. Different brain areas are involved in the generation of ASSRs. In this study we introduce a statistical framework to investigate possible effects of age on the spatial distribution of ASSR sources (generators) in the brain. ASSRs were obtained of young and older persons after presenting AM noises at 4 Hz and 40 Hz, two modulation frequencies that are present in continuous speech. Independent component analysis (ICA) was used as a linear decomposition to separate the brain source signals mixed by volume conduction in electroencephalography (EEG) recordings. An equivalent current dipole was then fitted for each source using a 4-shell spherical head model. The sources with significant responses to the presented modulation frequencies were determined based on Hotelling's T-squared test. The spatial distribution of these components was modeled by a Gaussian mixture model (GMM). Finally, the Kullback Leibler divergence was applied to provide a comparison between the GMM of ASSR sources in young and older persons. The result of the comparison showed a larger difference between young and older persons for 4 Hz ASSR sources compared to 40 Hz ASSR sources. This suggests that advancing age might have a larger effect on the spatial distribution of the 4 Hz ASSR sources compared to the 40 Hz ASSR sources. Acknowledgements This work was supported by the Research Council of KU Leuven through project OT/12/98. Keywords: Independent Component Analysis, Gaussian mixture model, spatial distribution, auditory steady-state response, amplitude modulation Conference: Second Belgian Neuroinformatics Congress, Leuven, Belgium, 4 Dec - 4 Dec, 2015. Presentation Type: Poster Presentation Topic: Methods and Modeling Citation: Darestani Farahani E, Wouters J and Van Wieringen A (2015). A statistical comparison of the spatial distribution of ASSR sources across age. Front. Neuroinform. Conference Abstract: Second Belgian Neuroinformatics Congress. doi: 10.3389/conf.fninf.2015.19.00005 Copyright: The abstracts in this collection have not been subject to any Frontiers peer review or checks, and are not endorsed by Frontiers. They are made available through the Frontiers publishing platform as a service to conference organizers and presenters. The copyright in the individual abstracts is owned by the author of each abstract or his/her employer unless otherwise stated. Each abstract, as well as the collection of abstracts, are published under a Creative Commons CC-BY 4.0 (attribution) licence (https://creativecommons.org/licenses/by/4.0/) and may thus be reproduced, translated, adapted and be the subject of derivative works provided the authors and Frontiers are attributed. For Frontiers’ terms and conditions please see https://www.frontiersin.org/legal/terms-and-conditions. Received: 13 Nov 2015; Published Online: 17 Nov 2015. * Correspondence: Mr. Ehsan Darestani Farahani, KU Leuven, Department of Neurosciences, Leuven, 3000, Belgium, e.darestani@gmail.com Login Required This action requires you to be registered with Frontiers and logged in. To register or login click here. Abstract Info Abstract The Authors in Frontiers Ehsan Darestani Farahani Jan Wouters Astrid Van Wieringen Google Ehsan Darestani Farahani Jan Wouters Astrid Van Wieringen Google Scholar Ehsan Darestani Farahani Jan Wouters Astrid Van Wieringen PubMed Ehsan Darestani Farahani Jan Wouters Astrid Van Wieringen Related Article in Frontiers Google Scholar PubMed Abstract Close Back to top Javascript is disabled. Please enable Javascript in your browser settings in order to see all the content on this page.

FEM METHOD FOR THE EEG FORWARD PROBLEM AND IMPROVEMENT BASED ON MODIFICATION OF THE SAINT VENANT'S METHOD

The finite-element method (FEM) is applied to solve the EEG forward problem. Two issues related to the implementation of this method are investigated. The first is the singularity due to the punctual dipole sources and the second is the numerical errors observed near the interface of different tissues. To deal with the singularity of the punctual dipole sources, three source modeling methods, namely, the direct, the subtraction and the Saint Venant's methods, are examined. To solve the problem of numerical instability near the interface of different tissues, a modification on the Saint Venant's method is introduced. The numerical results are compared with analytical solution in the case of the multilayer spherical head models. The advantages of the proposed method are highlighted.

Ultrastructure of sperm of the Spotted scat (Scatophagus argus, Linnaeus, 1766) observed by scanning and transmission electron microscopy

An investigation was conducted to understand the sperm cell morphology and ultrastructure of Spotted scat (Scatophagus argus) through scanning and transmission electron microscopy. The present study reveals that the sperm of S. argus can be differentiated into three major parts – an acrosome-less spherical head, a short mid-piece, and a cylindrical flagellum. The scat sperm cell had a mean total length of 21.32±1.80μm with the presence of ovoid electron-dense nucleus. The mean length and width of ovoid nucleus measured 1.44±0.34 and 1.54±0.33μm, respectively. The structural characteristics of the nucleus were found to be a shallow axial nuclear fossa and centriolar complex. The two centrioles were positioned nearly perpendicular to each other with a conventional “9+0” pattern in the proximal centriole. The short mid-piece was located laterally to the nucleus and contains 5 or 6 spherical and unequal-sized mitochondria. The mitochondria were separated from the axoneme by a cytoplasmic canal. The flagellum was inserted at the base of the nucleus with the presence of an axoneme structure of 9+2 paired micro tubules. The sperm flagellum had short irregular lateral fins. The present study reveals that Spotted scat sperm can be categorized as being of a “primitive or ect-aquasperm type” and belongs to the teleostean “type I” sperm. This is the first report on the morphology and ultrastructure of sperm in Scatophagidae family.

How are dysplastic hips different? A three-dimensional CT study.

Surgical correction of acetabular dysplasia can postpone or prevent joint degeneration. The specific abnormalities that make up the dysplastic hip are controversial. (1) What are the relative size, shape, and orientations of the typical nondysplastic hip? (2) How do these variables differ in the developmentally dysplastic hip? (3) Are there version differences between the acetabuli of dysplastic and nondysplastic hips? (4) Are there pairs of variables in which the change in one is always accompanied by a change in the other for both nondysplastic and dysplastic acetabuli? Of 117 consecutive three-dimensional (3-D) CT scans performed for hip dysplasia between March 1988 and October 1995, 48 met criteria of developmentally dysplastic hips by plain radiography. These were retrospectively compared with 55 pelvic 3-D CT scans culled from 81 consecutive scans performed for reasons other than hip dysplasia (ie, hip pain, trauma, infection) that did not affect the hip or pelvic landmarks. The 3-D reconstructions were orientated anatomically for standardization of the measurements to be compared. Representative 3-D volumes of the acetabular space were constructed from which we could measure anatomic positions and dimensional information. One author performed all image orientation and measurements. Nondysplastic acetabuli are essentially hemispheric with height equal to width and twice the depth. The dysplastic acetabuli were elongated in females (52.4 ± 6.2 mm for dysplastic versus 46.5 ± 4.6 mm for nondysplastic (mean difference, 5.0; 95% confidence interval [CI], 1.9-8.0; p = 0.002) and shallower in both females (18.7 ± 4.9 mm for dysplastic versus 23.6 ± 4.0 mm for nondysplastic; mean difference, 6.5; 95% CI, 4.4-8.5; p < 0.0001) and males (21.1 ± 4.8 mm for dysplastic versus 25.0 ± 4.3 mm for nondysplastic, mean difference, 5.3; 95% CI, 2.6-8.1; p = 0.0002); width was similar to that of nondysplastic hips. Acetabular openings were slightly more vertical than nondysplastic hips in females (5°; 95% CI, 1.9-8.1; p = 0.002) but not in male subjects. The dysplastic acetabuli were smaller in volume (18% in females, p = 0.002, and 19% in males, p = 0.0012) and had less space occupied by the femoral head compared with nondysplastic hips (p < 0.0001 for females, p < 0.0001 for males). Dysplastic hip midacetabulum was 4° more anteverted in females (95% CI, 0.5-6.8; p = 0.022) but not for males (p = 0.538). The upper dysplastic acetabulum was more retroverted in females and males (10.2°; 95% CI, 5.5-15; p < 0.0001, and 7.0°; 95% CI, 0.6-13.4; p = 0.032, respectively). Acetabular volumes in nondysplastic and dysplastic hips were related to acetabular width but not to length. Developmentally dysplastic acetabuli are not deficient in merely a single dimension but are globally deficient. The subluxated femoral head lies in the elongated and retroverted superior acetabulum, which becomes progressively shallower as the acetabulum increases in length. Focally deficient anterior or posterior femoral head coverage is uncommon. Current procedures that redirect the acetabulum, no matter how technically successful, cannot fully compensate for the incongruence of a spherical femoral head within a shallow and elongated acetabulum unless corrected at an early age when acetabular remodeling is possible. Early detection and treatment of acetabular dysplasia should be emphasized. Level III, prognostic study.

The acetabulum in Perthes' disease: a prospective study of 123 children.

PurposeWe assessed the radiographic changes of the acetabulum during the course of Perthes’ disease and investigated whether they were associated with femoral head sphericity 5 years after diagnosis.MethodsWe studied 123 children with unilateral Perthes’ disease, femoral head necrosis more than 50 % and age at diagnosis 6 years or older. Pelvic radiographs were taken at onset, 1 year and 5 years after diagnosis. Sharp’s angle, acetabular depth-to-width ratio (ADR) and lateral acetabular inclination were measured.ResultsCompared to the unaffected hips, the Perthes’ hips developed significantly higher Sharp’s angles (p < 0.001) and a higher proportion with an upward-sloping lateral acetabular margin (Perthes’ hips: 49 %, unaffected hips 1 %). The mean ADR values were significantly lower on the affected side at all stages (p < 0.001). ADR values at diagnosis were associated with a more spherical femoral head at the 5-year follow-up [odds ratio (OR) 1.012, 95 % confidence interval (CI) 1.002–1.022, p = 0.016]. None of the other acetabular parameters were significantly associated with the femoral head shape 5 years after diagnosis.ConclusionThe acetabulum developed an increasingly dysplastic shape in the course of Perthes’ disease. Early dysplastic changes of the acetabulum were not associated with a poor radiological outcome 5 years after diagnosis. Routine measurement and monitoring of acetabular changes in plain radiographs were of little prognostic value and can, therefore, hardly be recommended in clinical practice.

Reflection-mode micro-spherical fiber-optic probes for in vitro real-time and single-cell level pH sensing

pH sensing at the single-cell level without negatively affecting living cells is very important but still a remaining issue in the biomedical studies. A 70μm reflection-mode fiber-optic micro-pH sensor was designed and fabricated by dip-coating thin layer of organically modified aerogel onto a tapered spherical probe head. A pH sensitive fluorescent dye 2′,7′-Bis (2-carbonylethyl)-5(6)-carboxyfluorescein (BCECF) was employed and covalently bonded within the aerogel networks. By tuning the alkoxide mixing ratio and adjusting hexamethyldisilazane (HMDS) priming procedure, the sensor can be optimized to have high stability and pH sensing ability. The in vitro real-time sensing capability was then demonstrated in a simple spectroscopic way, and showed linear measurement responses with a pH resolution up to an average of 0.049 pH unit within a narrow, but biological meaningful pH range of 6.12–7.81. Its novel characterizations of high spatial resolution, reflection mode operation, fast response and high stability, great linear response within biological meaningful pH range and high pH resolutions, make this pH probe a very cost-effective tool for chemical/biological sensing, especially within the single cell level research field.

Computing interaural differences using idealized head models

The spherical model of the human head, attributable to Lord Rayleigh, accounts for important features of observed interaural time differences (ITD) and interaural level differences (ILD), but it also fails to capture many details. To gain an intuitive understanding of the failures, we computed ITDs and ILDs for a succession of idealized shapes approximating the human head: sphere, ellipsoid, ellipsoid plus cylindrical neck, ellipsoid plus cylindrical neck plus disk torso. Calculations were done as a function of frequency (100–2500 Hz) and for source azimuths from 10 to 90 degrees using finite-element models. The computations were compared to free-field measurements on a KEMAR manikin. The spherical head model approximated many measured interaural features, but the frequency dependence tended to be too flat in both ITD and ILD. The ellipsoidal head produced greater variation with frequency and therefore agreed better with the measurements, reducing the RMS discrepancies in both ITD and ILD by 35%. Adding a neck further increased the frequency variation. Adding the disk torso further improved the agreement, especially below 1000 Hz, decreasing the ITD discrepancy by another 21\%. The evolution of models enabled us to associate details of interaural differences with overall anatomical features. [Work supported by the AFOSR grant 11NL002.]

Nonphysiological factors in navigated TMS studies; confounding covariates and valid intracortical estimates.

Brain stimulation is used to induce transient alterations of neural excitability to probe or modify brain function. For example, single-pulse transcranial magnetic stimulation (TMS) of the motor cortex can probe corticospinal excitability (CSE). Yet, CSE measurements are confounded by a high level of variability. This variability is due to physical and physiological factors. Navigated TMS (nTMS) systems can record physical parameters of the TMS coil (tilt, location, and orientation) and some also estimate intracortical electric fields (EFs) on a trial-by-trial basis. Thus, these parameters can be partitioned with stepwise regression. The primary objective was to dissociate variance due to physical parameters from variance due to physiological factors for CSE estimates. The secondary objective was to establish the predictive validity of EF estimates from spherical head models. Variability of physical parameters of TMS predicts CSE variability. Event-related measurements of physical parameters were analyzed in stepwise regression. Partitioned parameter variance and predictive validity were compared for a target-controlled and a nontarget-controlled experiment. A control experiment (preinnervation) confirmed the validity of linear data analysis. A bias-free model quantified the effect of divergence from optimum. Partitioning physical parameter variance reduces CSE variability. EF estimates from spherical models were valid. Post hoc analyses showed that even small physical fluctuations can confound the statistical comparison of CSE measurements. It is necessary to partition physical and physiological variance in TMS studies to make confounded data interpretable. The spatial resolution of nTMS is <5 mm and the EF-estimates are valid.

SAR assessment on three layered spherical human head model irradiated by mobile phone antenna

AbstractWith the increasing application of wireless communication devices, mobile phone handsets are used by peoples of various age groups. This paper make an effort to asses the mobile phone radiation exposure effect on 4 years old, 8 years old children and an adult head model. Here, human head is modeled as a three layered sphere composed of skin, skull and brain. Hand held device model (with and without resistive sheet) having dipole antenna enclosed by plastic cover is used for human interaction. The software simulation performed by General Electro Magnetic Simulator, based on Finite Difference Time Domain technique yields Specific Absorption Rate and 3D-thermal distribution on spherical human head. Comparison of 1 g SAR, 10 g SAR values for adult and children head show that, children head absorbs more power than adult. Further, the application of resistive sheet on handset shows effective decrement in coupled power.

The Heat Upsetting Process for the Titanium Alloy Spherical Bone Screws

An advanced heat upsetting technology was studied according to the characteristics of the titanium alloy medical bone screws with spherical head. First, the reasons that punch demoulding is difficult during the upsetting forming have been discussed. Then the forming way with countersunk head in bottom and free forming on top was adopted, and the segmented upsetting die ranging in inner diameter was designed. Finally, the continuous heat upsetting process for medical bone screws was developed. The size, hardness and microstructure of the developed screws meet the standard requirements.

Three-layer-isotropic skull conductivity representation in the EEG forward problem using spherical head models.

We study the influence of different conductivity models within the framework of electroencephalogram (EEG) source localization on the white matter and skull areas. Particularly, we investigate five different spherical models having either isotropic or anisotropic conductivity for both considered areas. To this end, the anisotropic finite difference reciprocity method is used for solving the EEG forward problem. We evaluate a model of a numeric skull conductivity in terms of the minimum dipole localization/orientation error. As a result, both considered models of the skull reach the lowest dipole localization error (less than 6 mm), namely: i) single anisotropic layer and ii) three isotropic layers (hard bone/spongy bone/hard bone). Additionally, two different electrode configurations (10-20 and 10-10 systems) are tested showing that the error decreases almost as much as twice for the latter one though the computational burden significantly increases.

Impact of head modeling and sensor types in localizing human gamma-band oscillations.

An effective mechanism in neuronal communication is oscillatory neuronal synchronization. The neuronal gamma-band (30-100 Hz) synchronization is associated with attention which is induced by a certain visual stimuli. Numerous studies have shown that the gamma-band activity is observed in the visual cortex. However, impact of different head modeling techniques and sensor types to localize gamma-band activity have not yet been reported. To do this, the brain activity was recorded using 306 magnetoencephalography (MEG) sensors, consisting of 102 magnetometers and 102 pairs of planar gradiometers (one measuring the derivative of the magnetic field along the latitude and the other along the longitude), and the data were analyzed with respect to time, frequency, and location of the strongest response. The spherical head models with a single-shell and overlapping spheres (local sphere) have been used as a forward model for calculating the external magnetic fields generated from the gamma-band activity. For each sensor type, the subject-specific frequency range of the gamma-band activity was obtained from the spectral analysis. The identified frequency range of interest with the highest gamma-band activity is then localized using a spatial-filtering technique known as dynamic imaging of coherent sources (DICS). The source analysis for all the subjects revealed that the gradiometer sensors which measure the derivative along the longitude, showed sources close to the visual cortex (cuneus) as compared to the other gradiometer sensors which measure the derivative along the latitude. However, using the magnetometer sensors, it was not possible to localize the sources in the region of interest. When comparing the two head models, the local-sphere model helps in localizing the source more focally as compared to the single-shell head model.

The acoustical cues to sound location in the guinea pig (Cavia porcellus)

There are three main acoustical cues to sound location, each attributable to space- and frequency-dependent filtering of the propagating sound waves by the outer ears, head, and torso: Interaural differences in time (ITD) and level (ILD) as well as monaural spectral shape cues. While the guinea pig has been a common model for studying the anatomy, physiology, and behavior of binaural and spatial hearing, extensive measurements of their available acoustical cues are lacking. Here, these cues were determined from directional transfer functions (DTFs), the directional components of the head-related transfer functions, for 11 adult guinea pigs. In the frontal hemisphere, monaural spectral notches were present for frequencies from ∼10 to 20 kHz; in general, the notch frequency increased with increasing sound source elevation and in azimuth toward the contralateral ear. The maximum ITDs calculated from low-pass filtered (2 kHz cutoff frequency) DTFs were ∼250 μs, whereas the maximum ITD measured with low-frequency tone pips was over 320 μs. A spherical head model underestimates ITD magnitude under normal conditions, but closely approximates values when the pinnae were removed. Interaural level differences (ILDs) strongly depended on location and frequency; maximum ILDs were <10 dB for frequencies <4 kHz and were as large as 40 dB for frequencies >10 kHz. Removal of the pinna reduced the depth and sharpness of spectral notches, altered the acoustical axis, and reduced the acoustical gain, ITDs, and ILDs; however, spectral shape features and acoustical gain were not completely eliminated, suggesting a substantial contribution of the head and torso in altering the sounds present at the tympanic membrane.

Effect of anatomical variability on electric field characteristics of electroconvulsive therapy and magnetic seizure therapy: a parametric modeling study.

Electroconvulsive therapy (ECT) and magnetic seizure therapy (MST) are conventionally applied with a fixed stimulus current amplitude, which may result in differences in the neural stimulation strength and focality across patients due to interindividual anatomical variability. The objective of this study is to quantify the effect of head anatomical variability associated with age, sex, and individual differences on the induced electric field characteristics in ECT and MST. Six stimulation modalities were modeled including bilateral and right unilateral ECT, focal electrically administered seizure therapy (FEAST), and MST with circular, cap, and double-cone coils. The electric field was computed using the finite element method in a parameterized spherical head model representing the variability in the general population. Head tissue layer thicknesses and conductivities were varied to examine the impact of interindividual anatomical differences on the stimulation strength, depth, and focality. Skull conductivity most strongly affects the ECT electric field, whereas the MST electric field is independent of tissue conductivity variation in this model but is markedly affected by differences in head diameter. Focal ECT electrode configurations such as FEAST is more sensitive to anatomical variability than that of less focal paradigms such as BL ECT. In MST, anatomical variability has stronger influence on the electric field of the cap and circular coils compared to the double-cone coil, possibly due to the more superficial field of the former. The variability of the ECT and MST electric fields due to anatomical differences should be considered in the interpretation of existing studies and in efforts to improve dosing approaches for better control of stimulation strength and focality across patients, such as individualization of the current amplitude. The conventional approach to individualizing dosage by titrating the number of pulses cannot compensate for differences in the spatial extent of stimulation that result from anatomical variability.

FEM Analyses of the TOFD Technique in Unequal Thickness Component

The time-of-flight diffraction (TOFD) technique is a new ultrasonic nondestructive testing method. It utilize the longitudinal diffraction signal that generated from the defects, we can confirm whether there is a discontinuity in butt weld by the analysis of diffracted waves. This detection method has wide application prospects and detect flaws with high precision of localization and quantification. In this paper, two-dimensional numerical simulation of ultrasonic TOFD technique is carried out on unequal thickness butt weld of Drum Cylinder and Spherical Head, the propagation characteristics and laws of ultrasonic wave in unequal thickness component are analyzed by using finite element software ABAQUS. The simulation results show that the ABAQUS software can effectively simulate ultrasonic TOFD technique in such pressure vessel component, so the application range of ultrasonic TOFD technique will be extended.

Two-photon imaging of neural activity in awake mobile mice.

A method for functional, cellular-resolution imaging of neural populations in awake and mobile mice is presented here. The method is based on the use of a spherical treadmill, head restraint, and motion correction software that facilitate neural imaging in the awake brain with a fixed upright two-photon microscope. These approaches have proven to be applicable to a wide range of brain regions and should help further our understanding of how neuronal population activity within the brain's microcircuitry is connected to animal behavior.

Improved sound source localization in horizontal plane for binaural robot audition

An improved sound source localization (SSL) method has been developed that is based on the generalized cross-correlation (GCC) method weighted by the phase transform (PHAT) for use with binaural robots equipped with two microphones inside artificial pinnae. The conventional SSL method based on the GCC-PHAT method has two main problems when used on a binaural robot platform: 1) diffraction of sound waves with multipath interference caused by the contours of the robot head, which affects localization accuracy, and 2) front-back ambiguity, which limits the localization range to half the horizontal space. The diffraction problem was overcome by incorporating a new time delay factor into the GCC-PHAT method under the assumption of a spherical robot head. The ambiguity problem was overcome by utilizing the amplification effect of the pinnae for localization over the entire azimuth. Experiments conducted using two dummy heads equipped with small or large pinnae showed that localization errors were reduced by 8.91° (3.21° vs. 12.12°) on average with the new time delay factor compared with the conventional GCC-PHAT method and that the success rate for front-back disambiguation using the pinnae amplification effect was 29.76 % (93.46 % vs. 72.02 %) better on average over the entire azimuth than with a conventional head related transfer function (HRTF)-based method.

The initial transient and approach to self-similarity of a very viscous buoyant thermal

AbstractAn isolated buoyant thermal in very viscous fluid has been shown to attain a self-similar form at large times which grows as $t^{1/2}$ (Whittaker &amp; Lister J. Fluid Mech., vol. 606, 2008, pp. 295–324). For large values of the Rayleigh number $\mathit{Ra}$ (based on the conserved total buoyancy), the similarity solution is slender with a roughly spherical head at the top and a long tail that contains most of the buoyancy and extends down to the origin. We investigate the time-dependent behaviour of the thermal numerically; both the long-time behaviour in terms of perturbations to the similarity solution and the short-time evolution from a spherical initial condition. Using a spectral method, we find the growth rates of the linear perturbations and their spatial structure in similarity space. All eigenmodes decay monotonically for $\mathit{Ra}\lesssim 360$, while for larger $\mathit{Ra}$ the dominant (slowest decaying or fastest growing) eigenmodes are oscillatory with waves propagating up the tail. Above a critical value $\mathit{Ra}_c \approx 10\, 000$, the steady solution becomes unstable to a limit cycle. A one-dimensional reduction to horizontally integrated quantities hints at a theoretical explanation for the oscillatory behaviour, but does not reproduce the loss of stability. Investigation of the initial transient at large $\mathit{Ra}$ reveals that an initially spherical thermal can rise $O(100)$ times its initial diameter before approaching its final self-similar shape. The presence of a rigid horizontal floor below the thermal makes a quantitative difference of around 10 % to the rate of rise at large $\mathit{Ra}$.

Oleoresin Trichomes ofChamaecrista dentata(Leguminosae): Structure, Function, and Secretory Products

Premise of research. Despite the taxonomic and phylogenetic importance of secretory structures in Caesalpinioideae, especially in Chamaecrista species, the characterization of their external glands is scarce and fragmented. The structural features of these glands during the course of development and the histochemistry of the secretion products were studied to elucidate their anatomy, ontogeny, and secretion process, as well as to infer their functional role.Methodology. Samples of leaves and flowers were fixed and prepared following standard methods for scanning electron microscopy or embedding in resin for anatomy. Histochemical tests were carried out on fresh sections to detect the main classes of compounds present in the secretion.Pivotal results. The glands must be classified as trichomes since they originate from a single protodermal cell. They consist of a very short stalk and a large, multicellular spherical or oblong-shaped glandular head with a long, beak-shaped filiform projection. At the tricho...

Turban pin: an unusual cause of foreign body aspiration in young islamic adult.

Turban pin: an unusual cause of foreign body aspiration in young islamic adult.