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Animals use diverse solutions to land on vertical surfaces. Here we show the unique landing of the gliding gecko, Hemidactylus platyurus. Our high-speed video footage in the Southeast Asian rainforest capturing the first recorded, subcritical, short-range glides revealed that geckos did not markedly decrease velocity prior to impact. Unlike specialized gliders, geckos crashed head-first with the tree trunk at 6.0 ± 0.9 m/s (~140 body lengths per second) followed by an enormous pitchback of their head and torso 103 ± 34° away from the tree trunk anchored by only their hind limbs and tail. A dynamic mathematical model pointed to the utility of tails for the fall arresting response (FAR) upon landing. We tested predictions by measuring foot forces during landing of a soft, robotic physical model with an active tail reflex triggered by forefoot contact. As in wild animals, greater landing success was found for tailed robots. Experiments showed that longer tails with an active tail reflex resulted in the lower adhesive foot forces necessary for stabilizing successful landings, with a tail shortened to 25% requiring over twice the adhesive foot force., Siddall, Byrnes, Full, and Jusufi observe the function of the Asian flat-tailed gecko tail in gliding and landing on tree trunks in the field, complemented with mathematical and robotic models made of soft active materials. Altogether, their models show how geckos use an active tail reflex to brace the impact and reduce the risk of falling from landings on tree trunks.

Less invasive direct anterior approach (DAA) and dual mobility cup (DMC) are increasingly adopted in practice over the last decade. Their use aims to reduce, as much as possible, soft tissue dissection and dislocation rate. This study aims to present a novel surgical technique to reduce a DMC prosthesis during a DAA easily. A mildly modified version of the direct anterior approach is proposed. When leg lengths, stability, impingement, and tension have been checked, the trial stem is disassembled in situ, dislocated, and removed, leaving the space to exchange the trial double mobility head with the definitive one. When the definitive stem is inserted, the surgeon guides and helps the assistant to match the trunnion in the double mobility head. As soon as the components are matched, the traction is released, and the unit is impacted by an alternation of axial traction and release. Of 164 patients who underwent primary total hip arthroplasty (December 2016–May 2017) by a single surgeon, a double mobility cup through DAA and the “head-first” technique was performed in 26 patients (15.8%). The mean operative time was 130 min (85–220 min; SD 34.28). No significant complications occurred during the mean follow-up of 23.6 months. Specific difficulties can be anticipated when pairing dual mobility cup and direct anterior approach. The “head-first” technique is a useful technique in reducing the possible difficulties related to the reduction of double mobility cup through a less invasive direct anterior approach.

Background Head-first impacts with an aligned cervical spine cause some of the most severe types of injuries due to the risk of fractures and associated spinal cord injury. Sports, such as football, mountain biking and horseback riding, contribute to the incidence of spinal cord injury but there is potential to reduce the risk of these injuries through a helmet-mounted device. Methods A novel device, the Pro-Neck-Tor mechanism, was incorporated into a commercial football helmet and tested in head-first impact experiments. The Pro-Neck-Tor connects an inner and outer helmet shell, which upon head-first impact of a certain load, induces motion of the head away from the path of the following torso. Impacts were performed onto three impact surface angles with a flexion-inducing Pro-Neck-Tor mechanism. Findings Based on averaged data, the Pro-Neck-Tor provided a significant and consistent reduction in peak compressive neck forces compared to the unmodified football helmet in the conditions tested. In some impact conditions, the Pro-Neck-Tor increased the peak sagittal plane neck bending moments and impulse over that observed for the unmodified helmet. Interpretation The Pro-Neck-Tor with flexion escape is capable of lowering axial neck forces in head-first impacts compared to a conventional helmet by guiding the cervical column away from an aligned posture and into an eccentric loading scenario which published studies suggests frequently leads to no injury or to a less severe injury. Continued development and testing of the device are needed to optimize the altered neck loading and to drive the design toward a commercial configuration.

Head-first compressive impacts occur in motorcycle crashes and may result in serious to fatal neck injuries to riders. Equipment to protect the riders’ necks from these injuries are available in the market; however, their effectiveness in reducing injury risk is not clear, either due to the lack of scientific evidences or assessment with any prevalently accepted standard. This paper presents a finite element ligamentous neck model, developed as a computationally efficient tool, for future use in the computational phase of assessment process of neck protective equipment. The 3D cervical spine was generated using the mean statistical dimensions of vertebrae and proposed constitutive models, provided in the scientific literature. Ligaments, for the vertebra-vertebra and Hybrid III head–vertebra ligamentous joints, were introduced with the aid of published anatomical descriptions. For validation, the response of the head-neck system under compressive loadings and the flexion-extension bending stiffness of the neck at the segment level were compared against experimental data. The advanced CORrelation and Analysis (CORA) algorithm was applied on the validation responses to assess biofidelity of the model. The results indicate that the model is functional and meets ISO/TR9790 standard as a “good” biofidelic model.

Scientists whose first language is not English need to speak and write it constantly to gain fluency and become comfortable, says Lia Paola Zambetti. Scientists whose first language is not English need to speak and write it constantly to gain fluency and become comfortable, says Lia Paola Zambetti.

Now we will dive head first into the key areas of potential bias – systematic distortion – in user research with children. I present them in the order that they would occur chronologically in a given project as a chain and then group them into 18 steps. To be a master researcher one must understand and accept these biases and the failures they introduce in research with children.

Most of the recently available research and challenge data lack the meta-data containing any information about the patient position. This paper presents a tool for automatic rotation of CT data into a standardized (Head First Supine) patient position. The proposed method is based on the prediction of rotation angle with convolutional neural network, and it achieved nearly perfect results with an accuracy of 99.55 %. We provide implementations with easy to use example for both, Matlab and Python (PyTorch), which can be used, for example, for automatic rotation correction of VerSe2020 challenge data.

I received my doctorate in the field of Environmental Toxicology in 1982 from the University of Wisconsin-Madison. A few years later I had a rather unique opportunity to take over the operation of a laboratory with an established clientele. The majority of the analytical applications involved forensics. As a consequence, I was launched head first into the legal system and began my career as an expert witness.

Anticipatory eye movement promotes cranio-caudal sequencing during walking turns. Clinical groups, such as Parkinson's disease (PD), do not produce anticipatory eye movements, leading to increased risk of falls. Visual cues may promote anticipatory eye movement by guiding the eyes into the turn. This study examined if visual cues could train anticipatory eye movement. Ten neurotypical young adults and 6 adults with PD completed three blocks of walking trials. Trials were blocked by visual condition: non-cued baseline turns (5 trials), visually cued turns (10 trials), and non-cued post turns (5 trials). A Delsys Trigno (Delsys, Boston, MA) recorded horizontal saccades at 1024 Hz via electrooculography (EOG). Two Optotrak cameras (Northern Digital Inc., ON, Canada) captured body segment kinematics at 120 Hz. Initiation of segment rotation with respect to ipsilateral foot contact (IFC1) prior to the turn was calculated. Neurotypical young adults (NYA) produced typical cranio-caudal rotation sequences during walking turns. Eyes led (407 ms prior to IFC1), followed by the head (50 ms prior to IFC1), then trunk and pelvis. In contrast, PD produced no anticipatory eye or segment movement at baseline. During pre-trials the eyes moved 96 ms after IFC1 and segment movement was initiated by the pelvis followed by trunk and head segments. After visual cue training however, PD produced anticipatory eye movements 161 ms prior to IFC1, followed by the head 88 ms following IFC1 but ahead of trunk and pelvis onset. These results suggest visual cues assist in producing cranio-caudal control during walking turns in PD.

Introduction The causes of falls and resultant head injuries in people with epilepsy are complex and represent important clinical issues significantly impacting on safety, quality of life and long-term prognosis. A general solution for many years has been to provide helmets for head protection. There is poor understanding of the influencing risk factors and solutions to give person-centred clinical advice. Methods A focused narrative review was conducted to investigate the risk factors for seizure-related head injuries and evidence of current helmets to offer protection. Four databases were searched (Embase, Medline, PsycInfo and Cochrane Library) using combinations of text words and thesaurus terms for the retrieval of articles relating to seizure-related head injury. Articles for full analysis were selected by a ten item pre-defined inclusion criteria. Results Of 104 relevant studies longlisted 21 studies met four or more of the predefined criteria and included in this review. A further nine papers were included because they added additional relevant information. Conclusions Seizure-related head injury, although rare, may have serious consequences. High doses of antiepileptic/antiseizure drugs (AEDs/ASDs) and a prescription for three or more AEDs/ASDs are significant, modifiable, risk factors for head injury. Differentiating confusion due to post-ictal changes or concussion can be challenging. Seizure-related cardiac causes leading to injury due to ictal bradycardia or asystole is under investigated. More research is required to validate the protective benefit of various helmet designs in seizure-related head injury. It is striking that there are no International Standards for protective helmets in seizures.

We present a dependency tree linearization model with two novel components: (1) a tree-structured encoder based on bidirectional Tree-LSTM that propagates information first bottom-up then top-down, which allows each token to access information from the entire tree; and (2) a linguistically motivated head-first decoder that emphasizes the central role of the head and linearizes the subtree by incrementally attaching the dependents on both sides of the head. With the new encoder and decoder, we reach state-of-the-art performance on the Surface Realization Shared Task 2018 dataset, outperforming not only the shared tasks participants, but also previous state-of-the-art systems (Bohnet et al., 2011; Puduppully et al., 2016). Furthermore, we analyze the power of the tree-structured encoder with a probing task and show that it is able to recognize the topological relation between any pair of tokens in a tree.

We’re going to look at how to apply what we’ve learned to projects built with the Unreal Engine (UE4). One of the hallmarks of UE4 is the quality of the tools it provides for authoring in-engine content. Nowhere is this more evident than UE4’s material editor, which is one of the best visual material creation tools on the market today. This chapter is going to dive head first into using this tool. Like the previous chapter, it assumes that you already know enough about UE4 to get an object on screen and apply a material to it. If you haven’t gotten that far, there are lots of excellent resources online, and I recommend checking out a few to get your feet wet before returning to this chapter.

Aim To compare maternal and neonatal outcomes between the 'head first' and 'legs first' delivery methods during a second stage cesarean section. Methods We conducted a retrospective study between January 2009 and May 2015 at a large public university tertiary referral center. Included were all women who underwent cesarean delivery with a fully dilated cervix and a fetal head at the level of the ischial spines or below. The study population was divided into two groups according to way of fetal delivery: The 'legs first' (reverse breech) method and the 'head first' method. Demographics and maternal and fetal outcomes were retrieved for both groups. Results During the study period 447 women underwent a cesarean section while their cervix was fully dilated. Of them, 321 met the inclusion criteria: One hundred and twenty-one (38%) were delivered using the 'legs first' method and 200 (62%) were delivered using the 'head first' method. Indication for surgery and fetal head station was similar for both groups. While no difference in overall intraoperative uterine incision extension rate was observed, a higher rate of uterine incision extension was demonstrated in the 'head first' group in cases in which the second stage was longer than 180 min (33 vs 8 cases, P = 0.02). No differences in maternal postoperative complication rates and neonatal outcomes were observed. Conclusion Fetal extraction via the 'legs first' method during prolonged second stage of labor may lower maternal morbidity. Method of delivery does not seem to have an effect on neonatal outcomes.

The historical and clinical basis for classification of Freeman-Sheldon syndrome as a craniofacial syndrome and explanation of the rationale underlying this decision is provided. Correctly classifying the condition will avoid confusion and may help to clarify the vernacular employed and eventually aid in improving diagnosis.

In Vanuatu in the South Pacific, in order for boys to be legitimised as men, they jump head first from a great height with only rope made of vine leaves tied to their ankles to hopefully save their...

Fundamental safety measure for falling is to prepare flat and effective wide workplace with guardrails. However, their countermeasures may be difficult to apply for short-duration works and disaster relief works. In such cases, the fall arrest system has been applied to the height workplaces. This study focuses on fundamental characteristics of full body harness in various postures of wearer during falling. Three kinds of situation, such as (1) leg first fall, (2) head first fall, and (3) stop falling when the wearer body in parallel to the ground, were considered to recognize the performance. Experiments were carried out using 735N of human dummy, called HybridIII pedestrian 50%tile model in the automobile industry. The shock-absorber of the Lanyards used in this study were designed about 4 kN. Impact force acting on hook, head accelerations, and a chest displacement were measured during falling. From the results, not only the vertical acceleration of the human dummy but also horizontal were measured. Due to the horizontal acceleration, a huge bending moment acting on the dummy's neck observed in several situations. It indicates that the wearer may have risks of whiplash or more serious injuries such as dislocation of cervical vertebrae or spinal injuries. Chest deformations measured in this study were not also small for aged workers. It indicates that there are some risks of rid fractures or related chest injuries. The back of the head crashed aggressively to the D-ring of the full harness when the dummy rebounded due to stop falling by lanyard. Therefore, special helmet to resist the impact force due to D-ring, and the design force of shock-absorber should be reconsidered.

SKELETON IS A WINTER SPORT WHERE ATHLETES SLIDE A BOBSLEIGH TRACK HEAD FIRST ON A SLED. THE AIM OF THIS ARTICLE WAS TO IDENTIFY THE KEY PERFORMANCE INDICATORS TO OPTIMAL SKELETON PERFORMANCE. ONCE THESE ARE ESTABLISHED, THE STRENGTH AND CONDITIONING PROFESSIONAL CAN INTRODUCE TRAINING INTERV

Background A rugby tackle is an open and unpredictable event, which can lead to intentional or unintentional head-first impacts rather than the preferred ‘shoulder first’ technique. Objective To identify the effect of head-neck orientation as well as collision speed on the loads experienced at the upper cervical spine and the relevance in terms of injury risk from head-first impacts. Design Repeated ‘tackles’ were simulated using a 40 kg punch bag (simulated ball carrier) making contact against a fixed instrumented head and neck anthropometric test device (ATD). Setting Biomechanics laboratory. Patients (or Participants) A single head-neck ATD was used to complete all the trials. Interventions (or Assessment of Risk Factors) 10 repetitions were recorded in each of two speed ranges (low and high) and 3 ATD sagittal plane orientations (head-up [+20°], neutral [0°], and head-down [-20°]), 60 trials in total. Main Outcome Measurements Forces experienced at the equivalent of the C1 vertebra were measured by a load cell at the head joint of the ATD. ANCOVA (covariate=punch bag speed) and effect sizes were used to assess differences between tackle conditions. Results Low speed (2.34±0.18 m/s) tackles resulted in 37% lower peak impact forces compared with high speed (3.43±0.17 m/s) tackles. Total force on neck acted in multiple directions (75% in compression; magnitude of total force was 2.37±0.18 kN in neutral high speed condition) and it was substantially higher in the head-down orientation compared with the neutral (13%) and head-up orientation (17%). Conclusions Our findings support the idea that: 1) collision speed during a tackle affects the load experienced by the head-neck structures; 2) a neutral or head-up orientation of the head is preferred to a head-down orientation in the event of head-first impacts during simulated rugby tackle, which aligns with current Rugby Union coaching recommendations.

Only 6 cases of isolated unilateral rupture of the alar ligament have been previously reported. The authors report a new case and review the literature, morbid anatomy, and pathogenesis of this rare injury. The patient in their case, a 9-year-old girl, fell head first from a height of 5 feet off the ground. She presented with neck pain, a leftward head tilt, and severe limitation of right rotation, extension, and right lateral flexion of the neck. Plain radiographs and CT revealed no fracture but a shift of the dens toward the right lateral mass of C-1. Magnetic resonance imaging of the cervical spine showed signal hyperintensity within the left dens-atlas space on both T1- and T2-weighted sequences and interruption of the expected dark signal representing the left alar ligament, suggestive of its rupture. After 12 weeks of immobilization in a Guilford brace, MRI showed lessened dens deviation, and the patient attained full and painless neck motion. Including the patient in this case, the 7 patients with this injury were between 5 and 21 years old, sustained the injury in traffic accidents or falls, presented with marked neck pain, and were treated with external immobilization. All patients had good clinical outcome. The mechanism of injury is hyperflexion with rotation. Isolated unilateral alar ligament rupture is a diagnosis made by excluding associated fracture, dislocation, or disruption of other major ligamentous structures in the craniovertebral junction. CT and MRI are essential in establishing the diagnosis. External immobilization is adequate treatment.

Survival, in part, depends on an individual's ability to evade predators. In desert regions some lizard species have evolved head-first sand-diving strategies to escape predators. To facilitate this behaviour, a distinctive head morphology that facilitates sand-diving has evolved. This specialised head morphology may, however, come at a cost to other ecologically relevant functions, particularly bite force. Here, we investigated the relationship between morphology and function in a southern African lacertid lizard genus, Meroles, which consists of eight species that utilise different escape strategies, including sand-diving and running for cover. It was hypothesized that the specialised head morphology of diving species would negatively affect bite force capacity. We found that species from each escape strategy category differed significantly in head shape, but not bite force performance. A phylogenetic tree of the genus was constructed using two mitochondrial and two nuclear genes, and we conducted phylogenetic comparative analyses. One aspect of the head shape differed between the escape strategies once phylogeny was taken into account. We found that bite force may have co-evolved with head morphology, but that there was no trade-off between biting capacity and escape strategy in Meroles.

Optimum energy consumption in wireless sensitive networks plays an important role on network management. In the proposed model of this paper, first all the nods send the energy, station distance and density parameters to their fuzzy modules. According to each nod's fuzzy module outputs, a timer is activated for all nodes, which start reverse-counting from obtained value from fuzzy module. Timer of better nod comes to zero sooner and two best nods are selected in each zone (with the distance of r). One of them is introduced as superior cluster head and the other nods are connected to the closest cluster head. In addition, the cluster head not introduced as superior cluster head first collects data from neighbor's nods and then sends it to the superior cluster head after classifying data as package. The performance of the proposed model of this paper is compared with other methods and the preliminary results indicate that the proposed algorithm has increased first nod death time compared with other methods in the literature.

OBJECTIVE To simulate horizontally aligned head-first impacts with initial head protrusion using a human cadaveric neck model and to determine biomechanical responses, injuries, and injury severity. DESIGN Head-first impacts with initial head protrusion were simulated at 2.4 m/s using a human cadaver neck model (n = 10) mounted horizontally to a torso-equivalent mass on a sled and carrying a surrogate head. Macroscopic neck injuries were determined, and ligamentous injuries were quantified using fluoroscopy and visual inspection after the impacts. Representative time-history responses for injured specimens were determined during impact using load cell data and analyses of high-speed video. SETTING Biomechanics research laboratory. PARTICIPANTS Cervical spines of 10 human cadavers. MAIN OUTCOME MEASURES Injury severity at the middle and lower cervical spine was statistically compared using a 2-sample t test (P < 0.05). RESULTS Neck buckling consisted of hyperflexion at C6/7 and C7/T1 and hyperextension at superior spinal levels. Noncontiguous neck injuries included forward dislocation at C7/T1, spinous process fracture and compression-extension injuries at the middle cervical spine, and atlas and odontoid fractures. Ligamentous injury severity at C7/T1 was significantly greater than at the middle cervical spine. CONCLUSIONS Distinct injury mechanisms were observed throughout the neck, consisting of extension-compression and posterior shear at the upper and middle cervical spine and flexion-compression and anterior shear at C6/7 and C7/T1. Our experimental results highlight the importance of clinical awareness of potential noncontiguous cervical spine injuries due to head-first sports impacts.

The clerkship year is like being thrown head first into water, though the experience gradually becomes natural. An educator and an intern explore the developmental effects of the jarring moments that remind medical students that they're immersed in a strange new element.

To evaluate a prototype sagittal plane surrogate neck model designed to provide a biofidelic response to head-first impacts with a straightened cervical posture.Published biomechanical studies were used in the design to define the range of motion (ROM) and stiffness in both flexion-extension rotation and axial compression. The neck was tested in a series of head-first impacts on a drop tower to investigate the temporal aspects of the kinetic axial force response for the head and neck. A separate series of flexion-extension tests was conducted in a spinal motion simulator to assess its ROM and bending stiffness.In impacts with a 104 N axial preload, the surrogate head and neck displayed a bimodal response to force development in agreement with published studies of cadaveric head-first impacts. In bending without an axial preload, the neck had an ROM and bending stiffness representative of cadaveric human spines and it included a large neutral zone, but with the incremental addition of axial preload these metrics were somewhat reduced.The model appears suitable for studying the scenario of sagittal plane, aligned column impacts. Further design refinements are required to provide biofidelity in both sagittal bending and head-first impacts using a single level of axial preload. This would be necessary to study impact scenarios where considerable sagittal plane neck rotation occurs at impact. The model has identified some key concepts that must be considered for continued design and improvement of a dedicated dummy neck for head-first impacts.

Maternal and fetal morbidity of two different methods of delivering the baby during cesarean section performed in advanced labor when the fetal head is deeply engaged was assessed retrospectively, i.e. delivering as 'cephalic' with or without assistance to push up the fetal head from the vagina (head first or push method) and 'reverse breech extraction' (feet first or pull method). Records of 182 women with a single fetus in cephalic presentation, who had undergone cesarean section at cervical dilatation at > or =7 cm, with the vertex at or below zero station, were reviewed. Extension of the uterine incision occurred in significantly more women during 'cephalic' delivery as compared to 'reverse breech extraction' (22.8% versus 2.2%; p=0.001). Use of 'reverse breech extraction' is an attractive and safe alternative to the standard methods for intra-operative disengagement of a deeply impacted fetal head in order to reduce maternal and fetal morbidity.

One of the challenges facing teachers is to develop students' ability to understand a problem, use this knowledge to find a solution, and then apply what they have learned to a real-world situation. The Ohio Academic Standards, as do many other states' standards, call for applying mathematical knowledge and skill in other content areas and practical situations (INFOhio 2007). The project described here—to determine the volume of water in Norris Lake, Tennessee—satisfies Ohio Academic Standards for computing various attributes, including area and volume, and for developing a mathematical model. It also addresses a specific, practical need: Knowing the volume of the lake is critical to managing the flow of water over the dam, generating electricity, and assessing the environmental impact on fish and wildlife. The project allows students to take what they have learned about calculating areas and volumes, using maps and scales, and incorporating the use of technology to approximate the total volume of water in Norris Lake.

The rice paddy eel, Pisodonophis boro (P. boro), is of special interest because of its peculiar burrowing habits. P. boro penetrates the substrate tail-first, a technique common for ophichthids, but it is able to burrow head-first as well. P. boro exhibits three feeding modes: inertial feeding, grasping, and spinning. Rotational feeding is a highly specialized feeding mode, adopted by several elongate, aquatic vertebrates and it is likely that some morphological modifications are related to this feeding mode. The detailed morphology of the head and tail of P. boro is examined with the goal to apportion the anatomical specializations among head-first burrowing, tail-first burrowing, and rotational feeding. The reduced eyes, covered with thick corneas may be beneficial for protection during head-first burrowing, but at the same time decreased visual acuity may have an impact on other sensory systems (e.g. cephalic lateral line system). The elongated and pointed shape of the skull is beneficial for substrate penetration. The cranial bones and their joints, which are fortified, are advantageous for resisting high mechanical loads during head-first burrowing. The aponeurotic connection between epaxial and jaw muscles is considered beneficial for transferring these forces from the body to the head during rotational feeding. Hypertrophied jaw muscles facilitate a powerful bite, which is required to hold prey during spinning movements and variability in the fiber angles of subdivisions of jaw muscles may be beneficial for preventing the lower jaw from being dislodged or opened. Furthermore, firm upper (premaxillo–ethmovomerine complex) and lower jaws (with robust coronoid processes) and high neurocranial rigidity are advantageous for a solid grip to hold prey during rotational feeding. The pointed shape of the tail and the consolidated caudal skeleton are beneficial for their tail-first burrowing habits. It is quite likely that the reduction of the caudal musculature is related to the tail-first burrowing behavior because the subtle movements of the caudal fin rays are no longer required. J. Morphol., 2007. © 2007 Wiley-Liss, Inc.

Suprematism’s attempt to move beyond representation in painting coincided with an attempt to move beyond Russian Futurist poetry and literature. It was an attempt to go ‘beyond zero’. In making that move, however, Kasimir Malevich, creator of suprematism, needed to develop from Russian Futurism—particularly that of Velimir Khlebnikov— working within the Russian avant-garde. Through his painterly reliance on the square, Malevich not only worked in concert with Futurists such as Khlebnikov but ultimately elaborated on a literary theory bound by the constraints of language. In essence, Malevich’s Suprematism could not get ‘beyond zero’ until Khlebnikov’s Futurism got him there.

Two case studies are presented involving fatal falls of adult females from a height. One involved a launch at low speed from a balcony, and one involved a launch at high speed from the top of a cliff. Crime scene evidence obtained on the balcony itself provided a strong indication of homicide, but subsequent investigation showed that the fall was accidental. No crime scene evidence was obtained for the cliff fall since the fall initially appeared to be just another suicide from a popular suicide spot. Subsequent investigations indicated homicide based on measurements of cliff height, horizontal distance to the impact, and available runup distance, plus measurements of possible run, jump, and throw speeds. It was found that a female weighing 61 kg (134 lb) can be thrown at speeds up to 4.85 m/s by a strong male, more than enough to account for the estimated launch speed (4.5 m/s). Given the available 4.0 m runup distance, it was found that women of better than average rather than elite athletic ability can dive at speeds of about 3.5 m/s or jump feet first at speeds of about 4.0 m/s, both being less than the estimated launch speed. The decedent had no athletic ability and landed head first after falling through a height of 29 m.

interactions were observed between captive male Raukumara Tusked Weta, Motuweta riparia Gibbs. The repertoire of actions observed was ranked in order of increasing risk of injury and encounters were ranked in four levels of increasing aggression based on these actions. The repertoire of actions and level of aggression displayed was then compared with previously reported agonistic interactions in Hemideina (tree) weta. Observed differences in the repertoire of actions are related to differences in the cephalic and hind leg weaponry of the two genera. Motuweta riparia lack the hind leg weaponry common to Hemideina and position themselves in their burrows so as to begin interactions in a head to head orientation. If attacked from behind M. riparia will turn to assume this head to head orientation early on in the encounter. Hemideina position themselves head first into their refuges so as to present their heavily spined tibiae to intruders. While higher levels of aggression in both genera are head to head they are also influenced by the differences in cephalic weaponry. Motuweta riparia will engage in pushing contests by locking tusks with their opponent. Hemideina are restricted to lunging and grappling with one another, although the ultimate aggressive action in both taxa appears to be enclosing the head of an opponent with the mandibles. Differences also occur in the proportion of encounters that end without physical contact between these taxa (level I interactions), with most M. riparia encounters escalating to a moderate level of aggression (level II). However, the proportion of encounters in the two groups at the higher levels of aggression (III and IV), where the risk of injury becomes more likely, is similar.

Megan Woodworth's Eighteenth-Century Women Writers and the Gentleman's Liberation Movement jumps head first into the complex web of “politics, economics, and empire, as well as the last real ‘old b...

If mine were merely a mild head injury, which it was according to Scottish Intercollegiate Guidelines Network guidelines,1 I dare not think what a moderate or severe head injury must feel like. In May 2010, I was on Richard Roberts’ new sailing boat, returning from our triumph in the Scottish Islands Peaks Race, which combines sailing 140 miles with three mountain marathons (fastest monohull, third overall, top of our class). We were about to enter the Crinan Canal, the short cut from the Clyde to the west coast. It was raining, slippery on deck and there were ropes lying about. Presumably I slipped or tripped, no one is sure, but I definitely fell head first into the cockpit, hitting the left side of my head and ear, and shoulder. I was completely unconscious for about a minute, much to Richard's consternation, who thought I was dead. I came round with a sore head, a bleeding cut behind my ear and pretraumatic amnesia of seconds, comfortably above the ceiling of 15 on the Glasgow Coma Scale (GCS). I was really not too bad, able to go down into the cabin, and with help get my waterproofs and boots off, and lie down on a bunk. Within an hour I was reading the newspaper and regretting whatever stupidity had caused the fall. My left ear was a mess, bruised and bleeding from the cut inflicted by my glasses. After motoring along the Crinan Canal for a couple of hours, we had another think. We did not need a neurologist, we had two already—me and Richard. In any event, UK neurologists know little if anything about head injury and even less about ear injury (alas, the recent “The Bare Essentials of Head Injury” in Practical Neurology was not in the ship's library). …

Modernism has rendered ambiguous the role of the wall as a device of definition, confinement and separation and as carrier of symbolic dressing, for it can at one moment outdo itself with mass and at another deny its essence as diaphanous membrane such that it disappears as a physical phenomenon. The wall has been dissolved through technical means. This paper explores via Art, the aesthetics of the wall citing Schmarsow's two 'orders of the wall', an exaggerated function as a limit, or dissolution into a barrier that is permeable to space, these concepts of limiting and de-limiting generating an architecture conceived as space rather than surface. Historically, the wall lost its weight when painted with illusions of symbolic perspective thereby relieved of its passive role separating one area from another. Boulle's idea of creating a 'picture of infinity' inside buildings has evolved into James Turrell's 'Perceptual Cells'. The paper ends with discussion of the urban facade as multi-layered and transparen...

Refurbishing a practice is not something that should be dived into head first. It requires very careful planning to ensure that things go as smoothly as possible. Refurbishment is, however, a task that is never really finished.

Myosin-V transports intracellular cargo along an actin filament, using a 'hand-over-hand' mechanism that moves it forward in 36-nm steps before dissociating. To achieve long run lengths, the stepping of the two myosin heads must be coordinated. Recent evidence favours the idea that this coordination is achieved by intramolecular strain between the heads, so that myosin prefers to pick up its trailing head first to search for a new actin-binding site, and move cargo forward on the actin.

Current understanding of the biomechanics of cervical spine injuries in head-first impact is based on decades of epidemiology, mathematical models, and in vitro experimental studies. Recent mathematical modeling suggests that muscle activation and muscle forces influence injury risk and mechanics in head-first impact. It is also known that muscle forces are central to the overall physiologic stability of the cervical spine. Despite this knowledge, the vast majority of in vitro head-first impact models do not incorporate musculature. We hypothesize that the simulation of the stabilizing mechanisms of musculature during head-first osteoligamentous cervical spine experiments will influence the resulting kinematics and injury mechanisms. Therefore, the objective of this study was to document differences in the kinematics, kinetics, and injuries of ex vivo osteoligamentous human cervical spine and surrogate head complexes that were instrumented with simulated musculature relative to specimens that were not instrumented with musculature. We simulated a head-first impact (3 m/s impact speed) using cervical spines and surrogate head specimens (n = 12). Six spines were instrumented with a follower load to simulate in vivo compressive muscle forces, while six were not. The principal finding was that the axial coupling of the cervical column between the head and the base of the cervical spine (T1) was increased in specimens with follower load. Increased axial coupling was indicated by a significantly reduced time between head impact and peak neck reaction force (p = 0.004) (and time to injury (p = 0.009)) in complexes with follower load relative to complexes without follower load. Kinematic reconstruction of vertebral motions indicated that all specimens experienced hyperextension and the spectrum of injuries in all specimens were consistent with a primary hyperextension injury mechanism. These preliminary results suggest that simulating follower load that may be similar to in vivo muscle forces results in significantly different impact kinetics than in similar biomechanical tests where musculature is not simulated.

The objective of this experimental investigation was to find out what dynamic forces a bicycle helmet' retention system is subjected to when head impact accidents take place. Different helmet models were subjected to simulated accidents, of the type with the head first (with vertical and horizontal velocity) against a rigid asphalt surface. The chin strap forces developed in the accident simulations of the present study were low compared to the requirements of most of the existing standards for bicycle helmets. The arithmetic mean of the chin strap peak forces of all impacts was 42 N. Three types of helmets were investigated, one hard-shell helmet, one non-shell helmet and one ribbed helmet (large ventilation holes) with hard shell. A six-year-old child test dummy and a car-crash test facility with a piece of inclined asphalt road on the carriage were the main attributes of the study. The test dummy was suspended from the ceiling and was hit by the piece of asphalt road mounted on the stiff car-c...

No matter how hard I try, I cannot recall the moments just before I crashed on that September morning in 2007. It was my usual bike ride down the gravel path to work, when somehow, I fell, landing head first into the ground. A concerned jogger helped me down the hill, then my husband brought me to

Terrain parks and jumping features at ski resorts have become increasingly popular with skiers and snowboarders over the past decade. If a jumper were to land incorrectly, such as in an inverted posture where one lands on their head, the consequences can be devastating and can result in cervical spine fractures or dislocations and serious spinal cord injury. The objective of this study was to assess the potential for serious neck injury in head-first impacts onto snow surfaces with and without helmets. We conducted six paired head-first impact drop tests, with and without helmets on snow that varied from soft to hard. Drop tests were carried out with a head and neck assembly from a Hybrid III anthropomorphic test device using a custom designed drop carriage. The impact speed was 4.0 ± 0.1 m/s, representing an equivalent fall height of 0.82 m. The head was instrumented with three uniaxial accelerometers located at the center-of-gravity and a six-axis load cell was located at the upper neck. The results indicated that the helmets provided good head protection in the hard snow impacts, reducing head accelerations by as much as 48 %. Head accelerations were low in soft snow impacts both with and without a helmet. Overall, helmets were not an effective countermeasure to high neck loads, although a minor reduction was noted in the soft snow impacts. All tests resulted in neck loads that exceeded the injury assessment reference values for the neck. Notably in the hard snow impacts, the neck loads were more than double the injury assessment reference values for all tests. Because of the susceptibility of the neck to injury at the relatively low drop heights that we tested, efforts to prevent neck injuries should focus on education and training to avoid head-first impact. KEYWORDS: head injury, neck injury, head-first impact, helmet, anthropomorphic test device, snow impact Language: en

Research to date has shown that the large inertial load of the head-arms-trunk (HAT) is controlled within a few degrees in both the frontal and sagittal planes over the gait cycle. Also, there are limited reports of major attenuation of the head anteroposterior ( A P ) acceleration in spite of large inertial perturbations at the hips during weight bearing. These findings prompted further investigations into the kinematics and the active control of upper body balance. The first experiment found that the head A P acceleration was significantly attenuated (0.48 m s −2 ) compared with the hip (1.91 m s −2 ) and that the attenuation was gradual from the lumbar level to the neck. A second experiment recorded the EMG profiles of the paraspinal muscles at every second vertebrae level from C 7 to L 4 . The results demonstrated a ‘top-down’ anticipatory control which stabilized the head first, then the cervical level, the thoracic level, and finally the lumbar level. Because of the lack of stretching of these paraspinal muscles and the incorrect polarity of the otolith acceleration, it was argued that this balance control was anticipatory and not reflex.

An in vitro biomechanical study.To investigate atlas injury mechanisms due to horizontally aligned head-first impacts of a cadaveric neck model and to document atlas fracture patterns and associated injuries.Experimental atlas injuries have been created by applying compression or radial forces to isolated C1 vertebrae, dropping weight or applying sagittal moments to the upper cervical spine segments, or vertical drop testing of head-neck specimens or whole cadavers. Atlas injuries that commonly occur due to horizontally aligned head-first impacts have not been previously investigated.Horizontally aligned head-first impacts into a padded barrier were simulated at 4.1 m/s, using a human cadaver neck model mounted horizontally to a torso-equivalent mass on a sled and carrying a surrogate head. Atlantal radial force was computed using head and neck load cell data. Postimpact dissection documented atlas and associated injuries. Average atlantal radial force peaks and their occurrence times were statistically compared (P0.05) among the first local and global peaks using paired t tests.The first average local peak in radial atlantal force was significantly smaller (1240 vs. 2747 N) and occurred significantly earlier (24 ms vs. 46 ms) than the global force peak. Atlas injuries consisted of either 3- or 4-part burst fractures or incomplete lateral mass fracture unilaterally. Associated injuries included bony avulsion of the transverse ligament unilaterally and fractures of the occipital condyles, superior facets of the axis, or odontoid.The results indicated that the varied atlas fracture patterns were due primarily to radial forces causing outward lateral expansion of its lateral masses. Anterior and posterior arch fracture locations are dependent, in part, upon the cross-sectional arch dimensions. Transverse ligament rupture or bony avulsion is likely associated with real-life atlantal burst fractures.

Sperm competition favours an increase in sperm swimming velocity that maximises the chances that sperm will reach the ova before rival sperm and fertilise. Comparative studies have shown that the increase in sperm swimming speed is associated with an increase in total sperm size. However, it is not known which are the first evolutionary steps that lead to increases in sperm swimming velocity. Using a group of closely related muroid rodents that differ in levels of sperm competition, we here test the hypothesis that subtle changes in sperm design may represent early evolutionary changes that could make sperm swim faster. Our findings show that as sperm competition increases so does sperm swimming speed. Sperm swimming velocity is associated with the size of all sperm components. However, levels of sperm competition are only related to an increase in sperm head area. Such increase is a consequence of an increase in the length of the sperm head, and also of the presence of an apical hook in some of the species studied. These findings suggest that the presence of a hook may modify the sperm head in such a way that would help sperm swim faster and may also be advantageous if sperm with larger heads are better able to attach to the epithelial cells lining the lower isthmus of the oviduct where sperm remain quiescent before the final race to reach the site of fertilisation. © 2011 Society for Reproduction and Fertility.