Narrow Portion Research Articles

Porosity characteristics of the Eocene mixed-sediment reservoirs in the saline lacustrine basin, Qaidam, China

In recent years, significant progress has been achieved in the field of deep exploration in the Yingxi area of the Qaidam Basin. The Eocene was characterized by mixed sediments in the lacustrine basin. The area consists of lacustrine carbonate, detrital material, and mud. All rocks contain numerous salt minerals. Via core observation, physical property analysis, capillary pressure tests, image logging, and field emission scanning electron microscopy, results reveal that the rocks contain a double porosity system. The first are fractures and salt mineral dissolution pores possessing a large pore radius, and the second are cracks between the salts and dolomite intercrystalline pores with a small pore radius. These two types of pores caused the double-platform feature with a lower narrow portion and upper wide portion on capillary pressure curves. Overall, the physical properties of the rocks are deficient, with low porosity-ultra-low permeability. Moreover, pores and throats are generally acceptable. Mineralogical composition analysis based on electronic probe shows that the rocks possess a high content of both silicon and aluminum, but low content of iron and manganese. The average FeO content in the dolomicrite is 1.322%, and that of MnO is 0.060%, both of which are lower than average Fe or Mn content in hydrothermal dolomite. It is believed that the dolomicrite possesses a penecontemporaneous metasomatic formation mechanism. The dolomitization process produces a large number of shrunken intercrystalline pores. These kinds of matrix pores, functioning as storage space, constitute an important support factor for the sustained and stable production of oil and gas in the study area.

Jupiter's polar ionospheric flows: High resolution mapping of spectral intensity and line‐of‐sight velocity of H3+ ions

AbstractWe present a detailed study of the auroral emission at Jupiter, which uses data taken on 31 December 2012 with the long‐slit echelle spectrometer Cryogenic Infrared Echelle Spectrograph (European Southern Observatory's Very Large Telescope). The entire northern auroral region was observed using significantly more slit positions than previous studies, providing a highly detailed view of ionospheric flows, which were mapped onto polar projections. Previous observations of ionospheric flows in Jupiter's northern auroral ionosphere, using the long‐slit echelle spectrometer CSHELL (NASA Infrared Telescope Facility) to measure the Doppler‐shifted ν 2 Q(1,0−) line at 3.953 μm, showed a strongly subrotating region that was nearly stationary in the inertial magnetic frame of reference, suggesting an interaction with the solar wind. In this work, we observe this stationary region coincident with a polar region with very weak infrared emission, typically described as the dark region in UV observations. Although our observations cannot determine the exact mechanisms of this coupling, the coincidence between solar wind controlled ionospheric flows and a region with very low auroral brightness may provide new insights into the nature of the solar wind coupling. We also detected a superrotating ionospheric flow measured both at and equatorward of the narrow bright portion of the main auroral emission. The origin of this flow remains uncertain. Additionally, we detect a strong velocity shear poleward of the peak in brightness of the main auroral emission. This is in agreement with past models which predict that conductivity, as well as velocity shear, plays an important role in generating the main auroral emission.

Modeling of lithium plating induced aging of lithium-ion batteries: Transition from linear to nonlinear aging

A physics-based Li-ion battery (LIB) aging model accounting for both lithium plating and solid electrolyte interphase (SEI) growth is presented, and is applied to study the aging behavior of a cell undergoing prolonged cycling at moderate operating conditions. Cell aging is found to be linear in the early stage of cycling but highly nonlinear in the end with rapid capacity drop and resistance rise. The linear aging stage is found to be dominated by SEI growth, while the transition from linear to nonlinear aging is attributed to the sharp rise of lithium plating rate. Lithium plating starts to occur in a narrow portion of the anode near the separator after a certain number of cycles. The onset of lithium plating is attributed to the drop of anode porosity associated with SEI growth, which aggravates the local electrolyte potential gradient in the anode. The presence of lithium metal accelerates the porosity reduction, further promoting lithium plating. This positive feedback leads to exponential increase of lithium plating rate in the late stage of cycling, as well as local pore clogging near the anode/separator interface which in turn leads to a sharp resistance rise.

Anatomy of Lamina in the Subaxial Cervical Spine With the Special Reference to Translaminar Screws: CT and Cadaveric Analysis With Screw Trajectory Simulation.

A cadaveric study. Translaminar screws were initially developed for C2 fixation. Since then, their usage has expanded to include the subaxial cervical spine, and thoracic and lumbar spine. To the best of our knowledge, special anatomy for inserting translaminar screws in the subaxial cervical spine has not been studied. To report the special anatomy for inserting translaminar screws in the subaxial cervical spine. A total of 18 cadaveric spines were harvested from C3 to C7 and 1 mm computed tomography (CT) scans and 3D reconstructions were obtained. Bilateral translaminar screw entry points and trajectories were simulated at each level from C3 to C7 utilizing Kodak Carestream/Pacs Ver 10.2. Constructs were selected to achieve maximal bony purchase with 1 screw, designated the "primary screw." The contralateral screw, designated the "secondary screw," was selected to achieve the optimal allowable diameter possible while avoiding a simulated cortical breach, which was not always necessarily the "best purchase" diameter. Initial screw diameters selected were 3.5 mm; however, in the event that a narrower portion was encountered, then a 3.0 mm diameter screw was utilized instead. The crossing area of both screws were calculated geometrically. Maximal thickness of the lamina was considered in determining the diameter of screws. Whenever possible, 3.5 mm screws were selected in both lamina (3.5/3.5 mm); however, if a 3.5 mm screw was utilized as the primary screw, but the permissible range (P) for the secondary screw was <3.5 mm, then a hybrid construct was utilized (3.5/3.0 mm). In cases where P was <3 mm, then both screws were studied at 3 mm (3.0/3.0 mm). Screw diameters that optimized trajectory and bony purchase, while remaining within the permissible range, were analyzed, tabulated, and recorded. On CT, along the trajectory of the screws, the image was cut and measured in terms of screw length, the narrowest portion of the lamina, vertical angle, and horizontal angle in both primary and secondary screws. On the individually separated cervical spine segments in cadavers (11 of 18), we performed caliper measurements on the same portions that were measured on CT. It could not be exactly the same portions, however, due to the 3-dimensional characteristics of the specimens. For C3, only 1 specimen allowed 2 screws (3/3 mm), while the remaining specimens permitted a unilateral primary screw (3.5 or 3 mm) only. For C4, 37% of specimens allowed 2 screws (3.5/3 mm or 3/3 mm), but the rest allowed only a unilateral primary screw (3.5 or 3 mm). For C5, 58% allowed 2 screws (3.5/3.5, 3.5/3, or 3/3 mm). For C6, 89% of specimen allowed 2 screws (3.5/3.5, 3.5/3, or 3/3 mm). For C7, all levels allowed 2 screws (3.5/3.5, 3.5/3, 4/4, 4/3, 4.5/3, 4.5/3.5, or 4/3.5 mm). On CT, the average lengths of the 1- and 2-degree screws were 26.14 and 24.01 mm, respectively. The average vertical and horizontal angles were 22.26 and 40.66 degrees for the 1-degree screw, and 3.45 and 45.59 degrees for the 2-degree screw. On cadavers, the average lengths of the 1- and the 2-degree screws were 22.58 and 23.44 mm, respectively. The average vertical and horizontal angles were 23.67 and 54.44 degrees for the 1-degree screw, and 2.28 and 54.89 degrees for the 2-degree screw. This is a report of the anatomy of the lamina in the subaxial cervical spine with the special reference to translaminar screws. It was analyzed with CT and cadaveric spines along with simulated screw trajectories. For the 1-degree translaminar screw, the entry point is the distance of the diameter of desired screw superior to the inferior margin of lamina-spinous process junction. The trajectory should be targeted toward the most superomedial corner of lateral mass. For the 2-degree translaminar screw, the entry point is the distance of the diameter of desired screw below the superior margin of lamina-spinous process junction, and the target is the most superolateral corner of lateral mass, which is typically horizontal. Further studies are needed to assess the feasibility of translaminar screw insertion in the actual subaxial cervical spine.

Gross anatomy of the skull of hippopotamus (Hippopotamus amphibius)

Morphological studies were conducted on the skull of a hippopotamus brought to the Veterinary college for postmortem examination. Skull of the hippopotamus was huge and notable for its little brain case and high supra-orbital ridges. The skull had a larger splanchnocranium than the neurocranium. From the dorsal view, the skull had a watch glass appearance because of its narrow middle portion (at the region of maxillae) and wide caudal and rostral portions. Maxilla showed a large Eminenta canina and two infraorbital foramina leading to two separate infraorbital canals. The premaxilla lodged two huge incisors and just above the central incisor, there was a large rough eminence for the elevated nostrils. Three to four large rounded lacrimal bullae were seen on the floor of the bony orbit. Frontal bone presented a strongly convex smooth supra-orbital ridge that formed upper margin of the orbit which projected from the surface of the skull. The median sagittal crest was very high that diverged to accommodate the concave forehead in front. Temporal fossa was very extensive. Caudal surface of the skull showed a concave nuchal surface and the external occipital protuberance was in the form of a crest. The paramastoid process and external auditory process were very short. Bulla tympanica was conical with a pyramidal muscular process. Anatomical peculiarities of the skull and their functional significance are discussed.

How (much) do flowers vary? Unbalanced disparity among flower functional modules and a mosaic pattern of morphospace occupation in the order Ericales.

The staggering diversity of angiosperms and their flowers has fascinated scientists for centuries. However, the quantitative distribution of floral morphological diversity (disparity) among lineages and the relative contribution of functional modules (perianth, androecium and gynoecium) to total floral disparity have rarely been addressed. Focusing on a major angiosperm order (Ericales), we compiled a dataset of 37 floral traits scored for 381 extant species and nine fossils. We conducted morphospace analyses to explore phylogenetic, temporal and functional patterns of disparity. We found that the floral morphospace is organized as a continuous cloud in which most clades occupy distinct regions in a mosaic pattern, that disparity increases with clade size rather than age, and that fossils fall in a narrow portion of the space. Surprisingly, our study also revealed that among functional modules, it is the androecium that contributes most to total floral disparity in Ericales. We discuss our findings in the light of clade history, selective regimes as well as developmental and functional constraints acting on the evolution of the flower and thereby demonstrate that quantitative analyses such as the ones used here are a powerful tool to gain novel insights into the evolution and diversity of flowers.

Dependence of the 0.5 × (2e2/h) conductance plateau on the aspect ratio of InAs quantum point contacts with in-plane side gates

The observation of a 0.5 × (2e2/h) conductance plateau in asymmetrically biased quantum point contacts (QPCs) with in-plane side gates (SGs) has been attributed to the onset of spin-polarized current through these structures. For InAs QPCs with the same width but a longer channel length, there is roughly a fourfold increase in the range of common sweep voltage applied to the SGs over which the 0.5 × (2e2/h) plateau is observed when the QPC aspect ratio (ratio of length over the width of the narrow portion of the structure) is increased by a factor 3. Non-equilibrium Green's function simulations indicate that the increase in the size of the 0.5 × (2e2/h) plateau is due to an increased importance, over a larger range of common sweep voltage, of the effects of electron-electron interactions in QPC devices with a larger aspect ratio. The use of asymmetrically biased QPCs with in-plane SGs and large aspect ratio could therefore pave the way to build robust spin injectors and detectors for the successful implementation of spin field effect transistors.

Pedicle Fractures of Axis

Cervical spinal column anatomically can be divided two part as upper and lower cervical spine. Upper cervical spine consists of the foramen magnum, paired occipital condyles, atlas and axis. C2 is the largest structure with its unique shape and function in this segment. The pars interarticularis and the pedicle are differently located in axis in comparison with other vertebrae. These two parts can be confused in the axis because of their unique anatomical localization. The pedicle of axis is the portion beneath the superior facet and anteromedial to the transverse foramen. In the other hand, the pars interarticularis or isthmus of axis is the narrower portion between the superior and inferior articulating facets. Fracture located at the pedicle of axis is extremely rare. The publications in this subject are still at the case presentation level. The presumed mechanism of injury is axial compression occurring in association with an asymmetrical lateral or rotatory component of the atlas on axis. Computerized tomography images with bone window and three-dimensional reconstruction of images of axis are the gold standard in the neuroradiological imaging of fracture. There is no specific clinical symptom and finding in the clinical diagnosing of the pedicle fracture. The neck pain may probably be present and the only symptom in the patient with unilateral pedicle fracture of axis. In the management of axis pedicle fracture, it is important that the patient’s age, presence of neurological deficit, additional fracture, ligament damage, and instability of the fracture. Isolated single-sided pedicle fractures are usually fractured in the form of unfragmented fissures. Such kinds of fractures are stabile fractures of C2. There is no need for surgical treatment in such patients.

Measuring niche overlap between co-occurring Plectropomus spp. using acoustic telemetry and stable isotopes

Investigating niche overlap in exploited fish species can reveal behavioural information necessary to improve conservation and fisheries management at a species level. The present study examined spatial and dietary overlap between two co-occurring reef fish, namely Plectropomus leopardus and P. maculatus, at an inshore reef in the Great Barrier Reef Marine Park using acoustic telemetry and stable isotopes. Movements of tagged fish within an acoustic array of 19 receivers deployed along a narrow reef portion of Orpheus Island were monitored for up to 3 years. Although space use was similar between species, spatial overlap was rare and P. maculatus (n=30) was consistently deeper than P. leopardus (n=32). Dietary overlap between species was high based on overlapping δ15N and δ13C isotopic niches in muscle tissue (n=20). The complementary stable isotope and acoustic telemetry data revealed these species had similar isotopic niches but distinct space use patterns, which may be a product of competition for resources. These findings show species-specific behaviours within a genus commonly managed or reported as a single entity, and provide new information on partitioning of resources by Plectropomus spp. in inshore reef environments.

Parent material and pedogenic thresholds: observations and a simple model

Pedogenic thresholds, where multiple soil properties vary substantially and coherently in a narrow portion of a broad environmental gradient, are well-described on basaltic soils in Hawaii. One such threshold occurs along climate gradients where primary minerals virtually disappear, base saturation decreases sharply, and aluminum is mobilized within a narrow range of increasing rainfall. A recent study that evaluated thresholds along a climate gradient of non-basalt-derived soils on the South Island of New Zealand found that while base saturation declined steeply in a narrow range of rainfall on that gradient, the change was not coherent across soil properties; a substantial fraction of the Ca present in primary minerals (40–60 %) remained through the highest-rainfall sites ((Dixon et al. in J Geophys Res, doi: 10.1002/2016JF003864, 2016). We developed a simple model to explore potential mechanisms driving differences between basalt-derived and non-basalt soils. Incorporating a broader spectrum of mineral weathering rates (including some primary minerals that are highly recalcitrant to weathering) into simulated non-basalt than simulated basalt-derived soils (and accounting for the lower rates of evapotranspiration in New Zealand) was sufficient to simulate observed differences between these substrates. Further, we used the simple model to evaluate the consequences of rainfall variation in the short- (time step to time step) and long-term (a change in rainfall after 50,000 time steps). Results of these analyses demonstrated that year-to-year variation in rainfall could play an important role in controlling changes in the position of the pedogenic threshold during soil development.

Quantifying the effect of body mass index, age, and depression severity on 24-h activity patterns in persons with a lifetime history of affective disorders.

BackgroundPatients with affective disorders of different ages have been found to present weight changes and different circadian activity patterns. This study assessed the effects of age, Body Mass Index (BMI) and depression severity on the activity-rest cycle in persons with affective disorders using a novel multifactorial 24-h analysis method.MethodsTwo hundred and thirty-six participants aged between 14 and 85 years underwent 5 to 22 days of actigraphy monitoring (mean duration = 14 days). BMI was also recorded and symptom severity was assessed with the Hamilton Depression Rating Scale (HDRS). Participants were divided into two groups: healthy controls (n = 68) and participants with a lifetime diagnosis of affective disorders (n = 168). First, the multiple regression method was employed to formulate the circadian activity pattern in term of the factors age, BMI and HDRS. For each group, the functional linear analysis method was applied to assess the relative effects of the factors. Finally, Wald-tests were used to assess the contribution of each factor on the circadian activity pattern.ResultsIn the affective disorders group, higher BMI was associated with higher activity levels from 3 am until 5.30 am and with lower activity levels from 10 am until 10.30 pm. Older age was associated with less activity across the day, evening, and night - from 11 am until 5.30 am. Higher HDRS scores were associated with higher activity around 1:30 am. In healthy controls, the effects of BMI and age on activity patterns were less pronounced and affected a narrower portion of the 24-h period.ConclusionThese findings suggest that older age and higher BMI are linked to lower daytime activity levels. Higher BMI and worse symptom severity were also associated with nocturnal activity patterns suggestive of sleep disturbances. The influence of age and BMI on 24-h activity profiles appear to be especially pronounced in people with affective disorders.

Gating, Regulation, and Structure in K2P K+ Channels: In Varietate Concordia?

K2P K(+) channels with two pore domains in tandem associate as dimers to produce so-called background conductances that are regulated by a variety of stimuli. Whereas gating in K2P channels has been poorly understood, recent developments have provided important clues regarding the gating mechanism for this family of proteins. Two modes of gating present in other K(+) channels have been considered. The first is the so-called activation gating that occurs by bundle crossing and the splaying apart of pore-lining helices commanding ion passage. The second mode involves a change in conformation at the selectivity filter (SF), which impedes ion flow at this narrow portion of the conduction pathway and accounts for extracellular pH modulation of several K2P channels. Although some evidence supports the existence of an activation gate in K2P channels, recent results suggest that perhaps all stimuli, even those sensed at a distant location in the protein, are also mediated by SF gating. Recently resolved crystal structures of K2P channels in conductive and nonconductive conformations revealed that the nonconductive state is reached by blockade by a lipid acyl chain that gains access to the channel cavity through intramembrane fenestrations. Here we discuss whether this novel type of gating, proposed so far only for membrane tension gating, might mediate gating in response to other stimuli or whether SF gating is the only type of opening/closing mechanism present in K2P channels.

Systematization and description of the internal carotid arteries and their main ramifications at the brain base in turtles (Trachemys scripta elegans).

Thirty turtle brains (Trachemys scripta elegans) were injected with latex to systematize and describe the internal carotid arteries and their main ramifications at the brain base. The internal carotid arteries had one intercarotid anastomosis. At the level of the tuber cinereum, the internal carotid artery bifurcated into its terminal branches, the rostral and the caudal branches. The rostral branch emitted the rostral choroid artery, the orbital artery, and a series of middle cerebral arteries. After giving off the last middle cerebral artery, the rostral branch continued as the rostral cerebral artery in the cerebral longitudinal fissure, and had one anastomosis with its contralateral homologous artery, the rostral communicating artery, making the first rostral closure of the cerebral arterial circle. Next, the rostral cerebral arteries anastomosed forming a rostral interhemispheric artery, making the second rostral closure of the cerebral arterial circle. The internal carotid artery, after emitting its rostral branch, continued caudally as the caudal branch. The caudal branch ran caudally along the ventral surface of the mesencephalic tegmentum, emitted the caudal cerebral artery and the mesencephalic artery, and continued caudomedially while progressively narrowing, and anastomosed with its contralateral homologous artery, forming the basilar artery. The narrower portion also emitted the trigeminal artery. The anastomosis of the caudal branches closed the cerebral arterial circle caudally. The internal carotid arteries exclusively supplied the cerebral arterial circle of the turtle. Anat Rec, 299:1090-1098, 2016. © 2016 Wiley Periodicals, Inc.

Space Available for Sacroiliac Screws in the S1 Vertebral Body

Objectives: To define the maximal sagittal cross sectional dimensions of the S1 vertebral body and quantify the area available for safe placement of transverse sacroiliac (SI) screws. Methods: A laboratory investigation was performed using twelve fresh, frozen, non-preserved cadaveric pelvic specimens (six males, six females). The sacrum was dissected and removed from each pelvis. After the gross height and widths were measured, the sacra were split in the midsagittal plane and the dimensions of the first sacral segment were recorded. Then, starting from the center, the vertebral bodies were sequentially reamed in a medial to lateral direction in increasing one millimeter increments until a cortical breech occurred in the narrowest portion of the ala at the first sacral neural foramina. Using the diameter of the largest reamer, the cross-sectional area of space available for a transverse sacroiliac screw in the S1 body was calculated. Results: The cross-sectional area of space in the sagittal plane, corresponding to a transverse sacroiliac screw trajectory, of the first sacral vertebral body averaged 204 mm2 (range, 153 mm2 to 226 mm2 ), corresponding to a mean maximum reamer diameter of 16.1 mm (SD 1.08). The male and female sacra did not differ significantly with respect to overall size (mean height, 15.6 cm, SD 1.02; mean width 10.7 cm; SD 0.75) and the dimensions of the S1 body (mean height 28.41 mm, SD 2.23, mean depth 27.17 mm, SD 3.69). Conclusions: Our results improve upon our understanding of the surgical anatomic parameters of the upper sacral segment with respect to placement of transverse sacroiliac screw(s) by quantifying the cross-sectional area in the sagittal plane.

Understanding context dependence in the contribution of intraspecific variation to community trait–environment matching

Intraspecific trait variation (ITV) plays a potentially important role in determining functional community composition across environmental gradients. However, the importance of ITV varies greatly among studies, and we lack a coherent understanding of the contexts under which to expect a high vs. low contribution of ITV to trait-environment matching among communities. Here we first elaborate a novel conceptual framework posing specific hypotheses and predictions about the environmental and ecological contexts underlying the contribution of ITV to community trait turnover. We then empirically test these predictions in understory herbaceous plant communities in a montane environment, for three functional traits (flowering phenology, specific leaf area, and height). We found that different components of trait variation mapped onto different environmental axes, specifically reporting a greater contribution of ITV along non-climatic axes (e.g., soil properties, light) than along the main climatic axis (i.e., elevation), as predicted by the hypothesis that phenotypic plasticity (a major source of ITV) is greatest in response to conditions varying at a small spatial scale. Based on a variant of the niche-variation hypothesis, we predicted that the importance of ITV would be greatest in the lowest-diversity portion of the elevational gradient (i.e., at high elevation), but this prediction was not supported. Finally, the generally strong intraspecific responses to the gradient observed across species did not necessarily give rise to a high contribution of ITV (or vice versa) given (1) an especially weak or strong response of a dominant species driving the community-level trend, (2) differences among species in the direction of trait-environment response cancelling out, or (3) relatively narrow portions of the gradient where individual species abundances were high enough to have an important impact on community-level trait means. Our research identifies contexts in which we can predict that local adaptation and phenotypic plasticity will play a relatively large role in mediating community-level trait responses to environmental change.

Dynamic Analysis of a Base Isolated Building Having Zener Rheological Connections at Seismic Unidirectional Translations

The paper presents the physical model and the experimental results of a building having its base isolated with elastomeric and dissipative devices arranged in a functional configuration equivalent to that of the Zener rheological model.The harmonic motion of excitation at dominant frequency, which corresponds to a narrow band portion of the seismic composition spectrum, generates an inertial excitation force for the building modeled as a rigid-body with unidirectional displacement. Thus, the parameters of the unidirectional translation motion function of the inertial and of the linear viscoelastic characteristics of the Zener rheological model are analyzed.In essence, the amplitude of the displacement of the mass function of the fundamental spectral amplitude of the ground during an earthquake and the transmissibility or the isolation degree of the Zener rheological system are determined.

Mir-661: A key Factor in Embryo-Maternal dialog With Potential Clinical Application to Predict Implantation Outcome?

Mir-661: A key Factor in Embryo-Maternal dialog With Potential Clinical Application to Predict Implantation Outcome?

From Problem Taxa to Problem Solver: A New Miocene Family, Tranatocetidae, Brings Perspective on Baleen Whale Evolution

Miocene baleen whales were highly diverse and included tens of genera. However, their taxonomy and phylogeny, as well as relationships with living whales, are still a subject of controversy. Here, “Mesocetus” argillarius, a poorly known specimen from Denmark, is redescribed with a focus on the cranial anatomy. It was found to represent not only a new genus, Tranatocetus gen. nov., but also a new family; Tranatocetidae. The whales of this family have the rostral bones either overriding or dividing the frontals; the rostral bones are contacting the parietals and nasals dividing the maxillae on the vertex; the occipital shield is dorsoventrally bent. The tympanic bulla is particularly characteristic of this family featuring a short, narrow anterior portion with a rounded or squared anterior end and a wider and higher posterior portion that is swollen in the posteroventral area. A phylogenetic analysis including 51 taxa supports a monophyletic group comprising most Neogene and modern whales, with Tranatocetidae being possibly closer related to Balaenopteridae (rorquals) than to Cetotheriidae. Tranatocetidae exhibit a charahteristic bulla shape. In fact, all Neogene and modern mysticete families examined have a unique shape of the tympanic bulla that is diagnostic at family-level. Inclusion of problematic taxa like Tranatocetus argillarius in phylogenies brings new understanding of the distribution and diagnostic value of character traits. This underlines the need for re-examination of earlier described specimens in the light of the wealth of new information published in later years.

On the age and formation mechanism of the core of the Quadrantid meteoroid stream

The Quadrantid meteor shower is among the strongest annual meteor showers, and has drawn the attention of scientists for several decades. The stream is unusual, among others, for several reasons: its very short duration around maximum activity (≈12–14h) as detected by visual, photographic and radar observations, its recent onset (around 1835 AD Quetelet, L.A.J. [1839]. Catalogue des principles apparitions d’etoiles filantes) and because it had been the only major stream without an obvious parent body until 2003. Ever since, there have been debates as to the age of the stream and the nature of its proposed parent body, asteroid 2003 EH1.In this work, we present results on the most probable age and formation mechanism of the narrow portion of the Quadrantid meteoroid stream. For the first time we use data on eight high precision photographic Quadrantids, equivalent to gram–kilogram size, to constrain the most likely age of the core of the stream. Out of eight high-precision photographic Quadrantids, five pertain directly to the narrow portion of the stream. In addition, we also use data on five high-precision radar Quadrantids, observed within the peak of the shower.We performed backwards numerical integrations of the equations of motion of a large number of ‘clones’ of both, the eight high-precision photographic and five radar Quadrantid meteors, along with the proposed parent body, 2003 EH1. According to our results, from the backward integrations, the most likely age of the narrow structure of the Quadrantids is between 200 and 300years. These presumed ejection epochs, corresponding to 1700–1800AD, are then used for forward integrations of large numbers of hypothetical meteoroids, ejected from the parent 2003 EH1, until the present epoch. The aim is to constrain whether the core of the Quadrantid meteoroid stream is consistent with a previously proposed relatively young age (≈200years).

Morphometrics of the human thumb metacarpal bone: interest for developing an osseointegrated prosthesis.

Amputation of the thumb presents a serious insult to the hand and diminished quality of life for a patient physically, vocationally, and possibly psychologically. The aim of this study was to define the geometry of the thumb metacarpal in order to help create a standardized set of transcutaneous osseointegrated prostheses to treat patients who have suffered amputation of the thumb at the level of the metacarpophalangeal joint. A total of 80 metacarpals from 46 cadavers were studied. All soft tissues were removed and the thumb metacarpals were imaged using computed tomography. Three-dimensional models were constructed using images from the coronal, sagittal, and axial planes. Using HyperMesh™ CAD software, the bones were analyzed for overall length, radius of curvature, medullary canal diameter, cortical thickness, and distance to the isthmus, defined as the narrowest portion of the intramedullary canal. The average length of the first metacarpal was 47.6mm (±3.3mm, 39.2-56.9mm). The average radius of curvature was 55.5mm (±10.7mm, 33-78.9mm). Inner bone diameter, measured in two axes, was 10.5mm (±1.3mm, 5.4-18.7mm) for the major axis and 7.7mm (±0.9mm, 4.3-17.8mm) for the minor axis. The average cortical thickness was 1.4mm (±0.3mm, 0.7-3.1mm). The distance to the center of the isthmus from the distal end had an average length of 21.3mm (±1.9mm, 17-25mm). Using these findings a standardized set of intramedullary stems can be developed as a base for a transcutaneous osseointegrated prosthesis, helping to create a reliable method for treating patients with amputated thumbs.