Head Shape Research Articles

New Preoperative Simulations for the Future of Hydrocephalus Surgery

Ventricular puncture is a basic procedure that neurosurgeons learn in the early stages of their careers and is also performed in ventricular drainage and neuroendoscopic surgery. However, few neurosurgeons are confident in their ability to insert and place a ventricular catheter in the optimal position for ventriculoperitoneal(VP)shunting in a single pass. Even experienced neurosurgical consultants confident in difficult microsurgical procedures are uncomfortable with ventricular catheter placement in VP shunting. Moreover, many neurosurgeons believe that they will never perform a ventricular puncture from the posterior horn of the lateral ventricles. The reason for thinking that ventricular puncture via the anterior horn is safer and more accurate compared with the posterior approach is because the anterior approach can use facial landmarks such as eyes, nose, and ears. However, even with the anterior approach in VP shunting, it is more difficult than with ventricular drainage or neuroendoscopic surgery to achieve accurate placement owing to head rotation, and the success rate has been reported to be as high as 50%. In this article, I introduced "fool proof," which uses preoperative simulation to place a ventricular catheter in the optimal position according to the size and shape of each patient's head and ventricles. The first choice for VP shunting is the right parieto-occipital approach with a posterior horn puncture from Frazier's Point and, for L-P shunting, a paramedian puncture from the 2/3 or 3/4 lumbar interspace.

Experimental and numerical study on ventilated cavitation of high-speed projectile

In this study, ventilated cavitating flow characteristics around an axisymmetric projectile are investigated by combining experiments and numerical simulations. Experiments were carried out with a Split–Hopkinson pressure bar launch system and the pressure-equaling exhaust technology. Modular projectiles are designed to experimentally investigate the influence of head shape and ventilatory volume on flow characteristics. Large eddy simulation model is applied to obtain more flow field information. Compared with the conical head projectile, the hemispherical head projectile has a thinner attached cavity and more local detachment of the cavity. The statistical structure of the velocity and pressure fluctuations are analyzed by combining histograms and Q–Q diagrams. The results show that the pressure drag is dominant in the total drag and the periodic pulsation of the tail cavity and the stable vortex structure at the tail cause the variation of drag. The larger cavity volume changes the actual shape of the projectile, making the drag of the conical head projectile higher. The evolution characteristics of the cavitating flow field around the projectile with different ventilatory volumes are obtained, and the relationship between pressure fluctuation and chamber volume is derived. It is found that the reentrant jet causes a reverse flow at the nozzle, which leads to local pressure rise at the same interval. The above research work could contribute to the design and flow control of the ventilated cavity body.

Genomic underpinnings of head and body shape in Arctic charr ecomorph pairs.

Across its Holarctic range, Arctic charr (Salvelinus alpinus) populations have diverged into distinct trophic specialists across independent replicate lakes. The major aspect of divergence between ecomorphs is in head shape and body shape, which are ecomorphological traits reflecting niche use. However, whether the genomic underpinnings of these parallel divergences are consistent across replicates was unknown but key for resolving the substrate of parallel evolution. We investigated the genomic basis of head shape and body shape morphology across four benthivore-planktivore ecomorph pairs of Arctic charr in Scotland. Through genome-wide association analyses, we found genomic regions associated with head shape (89 SNPs) or body shape (180 SNPs) separately and 50 of these SNPs were strongly associated with both body and head shape morphology. For each trait separately, only a small number of SNPs were shared across all ecomorph pairs (3 SNPs for head shape and 10 SNPs for body shape). Signs of selection on the associated genomic regions varied across pairs, consistent with evolutionary demography differing considerably across lakes. Using a comprehensive database of salmonid QTLs newly augmented and mapped to a charr genome, we found several of the head- and body-shape-associated SNPs were within or near morphology QTLs from other salmonid species, reflecting a shared genetic basis for these phenotypes across species. Overall, our results demonstrate how parallel ecotype divergences can have both population-specific and deeply shared genomic underpinnings across replicates, influenced by differences in their environments and demographic histories.

Tex46 knockout male mice are sterile secondary to sperm head malformations and failure to penetrate through the zona pellucida.

Each year, infertility affects 15% of couples worldwide, with 50% of cases attributed to men. It is assumed that sperm head shape is important for sperm-zona pellucida (ZP) penetration but research has yet to elucidate why. We generated testis expressed 46 (Tex46) knockout mice to investigate the essential roles of TEX46 in mammalian reproduction. We used RT-PCR to demonstrate that Tex46 was expressed exclusively in the male reproductive tract in mice and humans. We created Tex46-/- mice using the Clustered Regularly Interspaced Short Palindromic Repeats (CRISPR)-CRISPR-associated protein 9 (Cas9) system and analyzed their fertility. Tex46 null spermatozoa underwent further evaluation using computer-assisted sperm analysis, light microscopy, and ultrastructural microscopy. We used immunoblot analysis to elucidate relationships between TEX46 and other acrosome biogenesis-related proteins. Mouse and human TEX46 are testis-enriched and encode a transmembrane protein which is conserved from amphibians to mammals. Loss of the mouse TEX46 protein causes male sterility primarily due to abnormal sperm head formation and secondary effects on sperm motility. Tex46 null spermatozoa morphologically lack the typical hooked sperm head appearance and fail to penetrate through the ZP. Electron microscopy of the testicular germ cells reveals malformation of the acrosomal cap, with misshapen sperm head tips and the appearance of a gap between the acrosome head and the nucleus. TEX46 is essential for sperm head formation, sperm penetration through the ZP, and male fertility in mice, and is a putative contraceptive target in men.

Cabbage (Brassica oleracea var. capitata) Development in Time: How Differential Parenchyma Tissue Growth Affects Leafy Head Formation.

This study aims to categorize the morphological changes during cabbage (B. oleracea ssp. capitata) development, seedling, rosette, folding, and heading, and to elucidate the cellular mechanisms of the leaf curvature, essential for the formation of the leafy head. We followed the growth of two cabbage cultivars with distinct head shapes (round and pointed) and one non-heading collard cultivar; we phenotyped the size and volume of the whole plant as well as the size, shape, and curvature of the leaves during growth. By integrating these phenotypic data, we determined the four vegetative stages for both cabbages. The histological phenotypes of microtome sections from five distinct leaf positions of the rosette, folding, and heading leaves at two timepoints during leaf growth were quantified and revealed variations in cellular parameters among leaf types, between leaf positions, and between the adaxial and abaxial sides. We identified two synergistic cellular mechanisms contributing to the curvature of heading leaves: differential growth across the leaf blade, with increased growth at the leaf's center relative to the margins; and the increased expansion of the spongy parenchyma layer compared to the palisade parenchyma layer, resulting in the direction of the curvature, which is inwards. These two processes together contribute to the typical leafy heads of cabbages.

Impact of Anterior and Posterior Vault Distraction Osteogenesis (A-PVDO) and 3D-Printed Positioning/Shaping Templates in Apert Syndrome: A Case Series Study.

This study seeks to examine the impact of anterior and posterior vault distraction osteogenesis (A-PVDO) in conjunction with 3D-printed positioning and shaping templates for the management of Apert syndrome. From January 2018 to February 2022, a retrospective analysis was conducted on 6 cases of Apert syndrome employing fronto-orbital 3D-printed positioning and molding templates. The cranium underwent surgical modification in accordance with the template's configuration and was affixed with absorbable plates. Subsequently, distraction devices were applied, encompassing both anterior and posterior craniotomies. The evaluation encompassed clinical outcomes, complications (including cerebrospinal fluid leakage and infection), safety, and the feasibility of the distraction osteogenesis procedure. Six patients diagnosed with Apert syndrome underwent treatment involving the integration of fronto-orbital 3D-printed positioning and shaping templates in conjunction with anterior and posterior cranial distraction osteoplasty. Follow-up durations ranged from 18 to 32 months (average: 22mo). No instances of fronto-orbital retraction, cerebrospinal fluid leakage, or intracranial infection were noted during the follow-up period. The sole reported complication entailed an infection at the extension rod site in 1 case. All patients conveyed satisfaction with the treatment outcomes. The application of 3D-printed positioning and shaping templates in tandem with anterior and posterior cranial distraction osteogenesis demonstrates efficacy in addressing Apert syndrome. Notably, significant enhancements in head shape and orbit were observed, and the incidence of postoperative complications such as cerebrospinal fluid leakage and infection remained minimal. Moreover, long-term follow-up affirmed stability.

Phenotypic Characterization and Husbandry Practice of Indigenous Chicken Ecotypes at West Guji, Ethiopia

This study was conducted with the objectives of characterization of indigenous chicken ecotypes and their husbandry practice at West Guji. A total of 204 households were randomly selected from two purposively selected woredas and 612 mature chickens were used for qualitative and quantitative traits data collection. The collected data were analyzed using the Statistical Package for Social Sciences (SPSS Version, 20) and the General Linear Model procedure (PROC GLM) of SAS. The qualitative data of feather distribution, plumage color, beak color, eye color, comb types, earlobe color, head shape, and shank color were collected. The result showed a significant difference between the districts (P< 0.05). Further, wing span, chest circumstance, body weight, and body length quantitative data were also recorded. The result revealed that there was a significant difference in quantitative traits in the study areas (P< 0.05). Egg production potentials, body weight, plumage color, hatchability, growth rate, and mothering ability were traits preferred by the household for female selection. The average age at first egg laying of indigenous chicken was 6.69±0.36 months and the number of eggs per hen per clutch was 12.16±0.26. The current finding revealed that about 93.5% of the observed chicken’s ecotypes were feathered and 6.45% were naked necks. The dominant chicken’s plumage colors identified were; brownish (29.28%), red (24.05%), and multicolor/ambesma (14.65%). The production systems practiced in the study area were extensive. Finally, phenotypic characterization of indigenous chicken ecotypes and performance evaluation should be supported by genetic characterization methods.

Evaluation of Head Height After Endoscopic Strip Craniectomy and Orthotic Therapy for Sagittal Craniosynostosis

Background: Achievement of normal head shape is one of the primary goals of all treatment modalities for craniosynostosis, in addition to maintenance of normal intracranial pressure and allowing normal brain development. Pre- and postoperative quantification of head shape in sagittal craniosynostosis has largely relied on cephalic index (width divided by anterior-posterior length of skull). However, many infants with sagittal craniosynostosis have a head that is short in addition to long and narrow. Height is not captured by the cephalic index. Methods: Patients who underwent endoscopic repair of sagittal craniosynostosis between 2016 and 2019 with available pre- and 1-year postoperative head computed tomography (CT) scans were identified. Age-matched controls with available CT scans were used for comparison. Twenty-one patients with sagittal craniosynostosis who underwent endoscopic repair, 10 preoperative, and 10 postoperative age-matched controls were identified. CT scans were measured with Analyze 12.0 software using soft tissue windows. Head height was defined as the vertical distance from the opisthocranion to the top of the head along a line crossing the tragus. Results: Patients with sagittal craniosynostosis had a shorter head height (mean 6.01 cm) than age-matched controls (mean 6.94 cm, P = .0003), and, after endoscopic repair and helmeting, the head height (mean 8.05 cm) was similar to age matched controls (mean 8.22 cm, P = .515). Conclusions: This head height measurement quantifies the third dimension of abnormal head shape in sagittal craniosynostosis. Additionally, it is adequately corrected in endoscopic repair with helmeting.

Subject-specific information enhances spatial accuracy of high-density diffuse optical tomography.

Functional near-infrared spectroscopy (fNIRS) is a widely used imaging method for mapping brain activation based on cerebral hemodynamics. The accurate quantification of cortical activation using fNIRS data is highly dependent on the ability to correctly localize the positions of light sources and photodetectors on the scalp surface. Variations in head size and shape across participants greatly impact the precise locations of these optodes and consequently, the regions of the cortical surface being reached. Such variations can therefore influence the conclusions drawn in NIRS studies that attempt to explore specific cortical regions. In order to preserve the spatial identity of each NIRS channel, subject-specific differences in NIRS array registration must be considered. Using high-density diffuse optical tomography (HD-DOT), we have demonstrated the inter-subject variability of the same HD-DOT array applied to ten participants recorded in the resting state. We have also compared three-dimensional image reconstruction results obtained using subject-specific positioning information to those obtained using generic optode locations. To mitigate the error introduced by using generic information for all participants, photogrammetry was used to identify specific optode locations per-participant. The present work demonstrates the large variation between subjects in terms of which cortical parcels are sampled by equivalent channels in the HD-DOT array. In particular, motor cortex recordings suffered from the largest optode localization errors, with a median localization error of 27.4 mm between generic and subject-specific optodes, leading to large differences in parcel sensitivity. These results illustrate the importance of collecting subject-specific optode locations for all wearable NIRS experiments, in order to perform accurate group-level analysis using cortical parcellation.

Isolated Sagittal Craniosynostosis: A Comprehensive Review.

Sagittal craniosynostosis, a rare but fascinating craniofacial anomaly, presents a unique challenge for both diagnosis and treatment. This condition involves premature fusion of the sagittal suture, which alters the normal growth pattern of the skull and can affect neurological development. Sagittal craniosynostosis is characterised by a pronounced head shape, often referred to as scaphocephaly. Asymmetry of the face and head, protrusion of the fontanel, and increased intracranial pressure are common clinical manifestations. Early recognition of these features is crucial for early intervention, and understanding the aetiology is, therefore, essential. Although the exact cause remains unclear, genetic factors are thought to play an important role. Mutations in genes such as FGFR2 and FGFR3, which disrupt the normal development of the skull, are suspected. Environmental factors and various insults during pregnancy can also contribute to the occurrence of the disease. An accurate diagnosis is crucial for treatment. Imaging studies such as ultrasound, computed tomography, magnetic resonance imaging, and three-dimensional reconstructions play a crucial role in visualising the prematurely fused sagittal suture. Clinicians also rely on a physical examination and medical history to confirm the diagnosis. Early detection allows for quick intervention and better treatment outcomes. The treatment of sagittal craniosynostosis requires a multidisciplinary approach that includes neurosurgery, craniofacial surgery, and paediatric care. Traditional treatment consists of an open reconstruction of the cranial vault, where the fused suture is surgically released to allow normal growth of the skull. However, advances in minimally invasive techniques, such as endoscopic strip craniectomy, are becoming increasingly popular due to their lower morbidity and shorter recovery times. This review aims to provide a comprehensive overview of sagittal craniosynostosis, highlighting the aetiology, clinical presentation, diagnostic methods, and current treatment options.

Undiagnosed sagittal synostosis as cause of "idiopathic" intracranial hypertension.

Idiopathic intracranial hypertension (IIH) is a rare condition in children, but if diagnosed needs to be promptly treated to avoid clinical sequalae. The main purpose of this paper was to test our clinical experience with a cohort of normocephalic children with craniosynostosis who do not present in the routine way to craniofacial services, due to the normal head shape and age, diagnosed with IIH. We retrospectively reviewed all children who were referred to neurosurgery from 2012 to 2022 for management of IIH on our prospectively kept database. We determined what treatments were offered and if there was an associated craniosynostosis. In total, 19 children were identified with an average age at referral of 11.5years (st dev 4.0years) with 11 male and 8 female. The most common presenting symptoms and signs were papilloedema (18/19), headaches (15/19), visual deterioration (9/19), nausea and vomiting (7/19) and diplopia (4/19). Five out of 19 children (26.3%) had a sagittal suture fused that was not identified at the time of treatment and all children were normocephalic. There is a cohort of children with IIH who will have concomitant craniosynostosis and ideally would benefit from cranial vault expansion as primary surgery rather than cerebrospinal fluid (CSF) diversion. We suggest all children with IIH requiring neurosurgical intervention have cross-sectional imaging to look for occult craniosynostosis prior to intervention.

Sexual dimorphism and allometry in the head and body size of two viperid snakes (genus Vipera)

Sexual dimorphism in the size and shape of the body and head is the result of manifold selective pressures acting on organisms. In snakes, sexual size dimorphism is common and has been well-studied. However, intersexual differences in relative head size and shape have attracted far less attention. Similarly, the allometric properties of head shape and size in snakes are poorly known. Here, we analyse sexual dimorphism in two viperid species: European adder Vipera berus (Linnaeus, 1758) and Steppe viper Vipera renardi (Christoph, 1861). We measured body length, tail length and several head characteristics: head length, head width, head height, pileus length, interorbital distance and internarial distance. Our findings were that males and females of both species did not differ in body length (SVL), but that males tended to have significantly longer tails; there were also significant differences in head characteristics – males tended to have higher heads, and larger internarial and interorbital distances. The head dimensions displayed negative allometry when compared against SVL but when scaled against head length, dimensions like head height and head width exhibited positive allometry. We argue that these differences may be related to sexual selection and that the wider heads may also serve as antipredatory signal.

Craniosynostosis-associated variants in the IL-11R complex: new insights and questions.

Skull growth involves the expansion of both the flat calvarial bones of the skull and the fibrous marginal zones, termed sutures, between them. This process depends on co-ordinated proliferation of mesenchymal-derived progenitor cells within the sutures, and their differentiation to osteoblasts which produce the bone matrix required to expand the size of the bony plates. Defects lead to premature closure of these sutures, termed craniosynostosis, resulting in heterogeneous head shape differences due to restricted growth of one or more sutures. The impact on the individual depends on how many and which sutures are affected and the severity of the effect. Several genetic loci are responsible, including a wide range of variants in the gene for the interleukin 11 receptor (IL11RA, OMIM#600939). Recent work from Kespohl and colleagues provides new insights into how some of these variants influence IL-11R function; we discuss their influences on IL-11R structure and IL-11 function as a stimulus of osteoblast differentiation.

Prevalence and correlation with sex, age, and dental status of bone apposition at the mandibular angle and radiographic alterations of the temporomandibular joints: a retrospective observational study in an adult Swiss population

BackgroundThe purpose of this study was to determine the prevalence of radiographic changes in the mandibular angle (bone apposition) and osseous alterations in the temporomandibular joints (TMJs) in the adult population of Switzerland. In addition, the study intended to investigate possible correlations between the two sites of contour bone changes (mandibular angle and TMJ) and to analyze various patient-related factors, including sex, age, dental status, and medical history.MethodsPanoramic radiographs of 600 patients distributed into six age groups (283 females, 317 males, aged 20 to 79 years) were included to evaluate radiographic changes. The bone in the mandibular angle region and the shape of the condylar heads were examined for contour changes (bone apposition at the jaw angles and osseous changes of the TMJs). General estimating equations, binormal tests, and chi-squared tests were used for statistical analysis.ResultsApproximately half of the mandibular angles (47.8%) showed bone apposition, mostly bilateral. TMJ alterations were less common (27%), often unilateral, with flattening being the most frequent finding. No significant correlation was found between the two sites. Bone apposition at the mandibular angle showed a significant male predominance, whereas TMJ changes did not differ by sex. Alterations in both sites increased with age, and were not related to dental status or analgesic use.ConclusionsBone apposition at the mandibular angle should be interpreted as part of the natural functional adaptation of the bone associated with aging. Assuming that parafunctional habits may influence the development and progression of alterations in the mandibular angle or TMJs, the presence of radiographic changes in these areas should prompt dental clinicians to investigate further in this direction.Trial registrationThe study was approved by the Swiss Association of Research Ethics Committees (swissethics), BASEC reference number: 2020–00963 (25.05.2020).

The Tragic Concept of Love and Madness in the Dramatic Literature of Farhad Nazerzadeh Kermani

The purpose of this article is to investigate the symbolic and symbolic aspects of the play "Window on the Wind “written by Professor Farhad Nazerzadeh Kermani with an interpretive anthropological approach. In the statement of interpretive anthropology, Clifford Geertz considers two important processes of emic-etic research as the fundamental elements of the interpretation of works of art. A Window on the Winds has been able to put the anthropological context of the drama in a link between culture, man, and nature, and by creating tribal music, it has also mixed the archetypes of the people of Kerman. In the play "Window on the Winds", from the title to the ending, the mixing of the culture of the two characters of Sanobar (female) and Mozaffar (man) in the imaginary self-made nature of Badabad, forms an interpretive anthropological triangle based on Geertz's theory on the interrelationships of "human", "culture" and "nature" and to place it in the category of semantic dramas of ecology. After eight months away, Mozaffar returned to his hometown of Badabad, Kerman, and under the influence of the false reports of monkey play, he became pessimistic towards his pregnant wife Sanobar. Therefore, to protect his reputation, he decides to punish Sanobar and takes her to the top of a hill in the desert at night with a rope in one hand and a lantern in the other hand, and ties her to a stone shaped like a donkey's head Kharsang), A big stone on a hill in the shape of a donkey's head is the punishment. He slowly walks away with the hyena-like sound of bad friends, with the assumption that if the fir tree is innocent, it will be saved by the nocturnal singers, and if it is guilty, it will become the prey of wild animals. Signs and meanings in this play express two important aspects of cultural and interpretive anthropology. The findings show that the author was able to create new symbols suitable for the culture and nature of the people of the region. There are about twenty-seven native, tribal, mental, religious, and imaginary symbols in this play, which places it in the ranks of notable ethnographic symbolist plays this research was prepared based on the method of descriptive-analytical and library-documentary studies and it was also analyzed using the qualitative content analysis method.

Current understanding of children's head shape and its impact on health: a cross-sectional study among pediatric medical staff in China.

Head shape problems are common in infancy and early childhood, and thus their early identification and management can benefit the health of children. This study aimed to investigate pediatric healthcare professionals' existing knowledge of children's head shape abnormalities and their associated effects in China, providing guidelines for future clinical interventions, training, and interdisciplinary collaboration. We conducted a survey among pediatric medical staff, encompassing various age groups, genders, hospitals, and professional levels. The electronic questionnaire queried respondents' basic information, knowledge pertaining to head shape issues, diagnosis and treatment approaches, and the clinical development status of head shape problems. All surveys and data collection were conducted anonymously. A total of 214 valid questionnaires were collected. Differences in the level of understanding among medical staff regarding head shape issues were observed. Medical staff in tertiary care facilities showed the highest proficiency in diagnosing and treating positional plagiocephaly and cranial asymmetry (P<0.05), while those in primary care facilities exhibited the lowest competency in diagnosing head shape abnormalities (P<0.05). Most medical staff had a partial understanding of specific aspects of head shape issues, such as identifying high-risk individuals (n=144, 67.29%), making diagnoses (n=176, 82.24%), and understanding the consequences (n=151, 70.56%), with no significant differences across medical facilities of various levels. Additionally, 99.07% (n=212) of the medical staff believed that head shape measurements should be included as a routine component of pediatric physical examinations, and 75.23% (n=161) incorporate head shape assessment as part of their routine physical examination. Furthermore, 91.12% (n=195) of the medical staff received consultations on children's head shape issues, with a higher prevalence in secondary and tertiary care facilities. Finally, 93.97% (n=201) of the participants expressed the need for further education and knowledge on pediatric head shape, with no significant differences across medical facilities of various levels. There is a limited understanding among medical personnel in China regarding children's head shape issues. Therefore, it is imperative to enhance training and educational initiatives for medical staff in China, with the goal of enhancing their awareness and knowledge regarding children's head shape problems.

Experimental evidence for adaptive divergence in response to a warmed habitat reveals roles for morphology, allometry and parasite resistance.

Ectotherms are expected to be particularly vulnerable to climate change-driven increases in temperature. Understanding how populations adapt to novel thermal environments will be key for informing mitigation plans. We took advantage of threespine stickleback (Gasterosteus aculeatus) populations inhabiting adjacent geothermal (warm) and ambient (cold) habitats to test for adaptive evolutionary divergence using a field reciprocal transplant experiment. We found evidence for adaptive morphological divergence, as growth (length change) in non-native habitats related to head, posterior and total body shape. Higher growth in fish transplanted to a non-native habitat was associated with morphological shape closer to native fish. The consequences of transplantation were asymmetric with cold sourced fish transplanted to the warm habitat suffering from lower survival rates and greater parasite prevalence than warm sourced fish transplanted to the cold habitat. We also found divergent shape allometries that related to growth. Our findings suggest that wild populations can adapt quickly to thermal conditions, but immediate transitions to warmer conditions may be particularly difficult.

Resource instability undermines predictable plasticity-mediated morphological responses to diet in a postglacial fish.

Phenotypic plasticity has been presented as a potential rapid-response mechanism with which organisms may confront swift environmental change and increasing instability. Among the many difficulties potentially facing freshwater fishes in recently glaciated ecosystems is that of invertebrate prey communities becoming significantly altered in species composition and relative abundance. To test how the rapidity of diet resource change may affect phenotypic responses during development, we subjected juvenile brown trout to pelagic-type or littoral-type diets that alternated either daily, sub-seasonally, or not at all over a single growth season. The proportional intake of each diet was traced with stable isotopes of carbon and nitrogen and modelled with morphometric data on head and jaw shape. While those trout exposed to a single diet type developed predictable morphologies associated with pelagic or littoral foragers, those raised on alternating diets expressed more unpredictable morphologies. With extreme (daily) or even sub-seasonal (monthly) resource instability, the association of diet type with the phenotype was overwhelmed, calling into question the efficacy of plasticity as a means of adaptation to environments with rapidly fluctuating prey resources.

Ctenocephalides orientis and Ctenocephalides felis in Thailand: Head geometry by species, sex and geography.

Fleas in the genus Ctenocephalides serve as biological vectors or intermediate hosts of microorganisms such as bacteria, rickettsia, protozoa and helminths. Ctenocephalides felis has a worldwide distribution, while C. orientis has long been considered as a subspecies of C. felis in Asia. To help the morphological recognition of these two species and further explore their differences, we used the geometric morphometric approach applied to the head. Both sexes were examined. Five anatomical landmarks of the head were used, and to capture the curvature of the front head, 10 semilandmarks were added. There was a consistent difference in species classification accuracy when considering landmarks only versus their combination with semilandmarks, suggesting the importance of the curve of the head as a taxonomic signal. Using or not the labels in the reclassification analyses, the head shape allowed by itself almost perfect recognition of the two species, in both sexes, even after adjustment for prior probabilities. The same approach disclosed a high level of sexual size and shape dimorphism in both species. The contribution of size variation to the discrimination by shape was much more important between sexes (from 27% to 45%) than between species (from 0.7% to 7.1%). Nevertheless, in our data, size never could represent a way to reliably recognise the sex of an individual, even less its species. Geographical variation in head shape could only be explored for the C. orientis sample. No significant correlation of morphometric variation with geography could be detected, which would be consistent with gene flow between Thai provinces. The geometric morphometric approach of the flea head, when it incorporates head curves, is a promising tool for rapid, economical, and accurate species and sex identification. It is, therefore, a useful tool for future epidemiological and demographic studies.

Head stabilization apparatus for high-resolution ophthalmic imaging.

Head movement must be stabilized to enable high-quality data collection from optical instrumentation such as eye trackers and ophthalmic imaging devices. Though critically important for imaging, head stabilization is often an afterthought in the design of advanced ophthalmic imaging systems, and experimental devices often adapt used and/or discarded equipment from clinical devices for this purpose. Alternatively, those seeking the most stable solution possible, including many users of adaptive optics ophthalmoscopy systems, utilize bite bars. Bite bars can provide excellent stability but are time consuming to fabricate, decreasing imaging efficiency, and uncomfortable for many patients, especially the elderly and/or those with prosthodontics such as dentures who may refuse participation in a study that requires one. No commercial vendors specifically offer head mount solutions for experimental ophthalmic imaging devices, resulting in nearly every custom device having a different solution for this commonly encountered problem. Parallelizing the head stabilization apparatus across different custom devices may improve standardization of experimental imaging systems for clinical trials and other multicenter investigations. Here we introduce a head mount design for ophthalmic imaging that is modular, adjustable, and customizable to the constraints of different experimental imaging configurations. The three points of head contact in our solution provide excellent stabilization across a range of head sizes and shapes from small children to adults, and the ease of adjustment afforded by our design minimizes the time to get participants stabilized and comfortable.