Sharp Head Research Articles

Computational analysis of the anode-directed streamers propagation in atmospheric pressure C4F7N/N2 mixtures

In recent years, interest in synthetic C4F7N as a gas insulator has been growing due to its unique insulation properties and low global warming potential. In spite of this, very few studies are devoted to the analysis of the electric breakdown of C4F7N and its mixtures with other dilutants such as CO2 and N2. In the present paper, we use a two-dimensional fluid model to analyze the electrical breakdown of the atmospheric pressure C4F7N/N2 mixture. We establish the influence of the C4F7N fraction in the mixture and the cathode voltage rise rate on the breakdown voltage. We find that the ratio between the electron attachment frequency and the voltage rise rate defines the streamer parameters. Namely, if the time scale of electron attachment to C4F7N is much faster than the voltage rise rate, the plasma electronegativity of the streamer body and of its head is extremely high, and it is difficult to define exactly the streamer head location. In the opposite case of the fast rise rates, the conventional streamers with sharp heads were obtained.

Multiple Kernel Synthesis of Head CT Using a Task-Based Loss Function

In CT imaging of the head, multiple image series are routinely reconstructed with different kernels and slice thicknesses. Reviewing the redundant information is an inefficient process for radiologists. We address this issue with a convolutional neural network (CNN)-based technique, synthesiZed Improved Resolution and Concurrent nOise reductioN (ZIRCON), that creates a single, thin, low-noise series that combines the favorable features from smooth and sharp head kernels. ZIRCON uses a CNN model with an autoencoder U-Net architecture that accepts two input channels (smooth- and sharp-kernel CT images) and combines their salient features to produce a single CT image. Image quality requirements are built into a task-based loss function with a smooth and sharp loss terms specific to anatomical regions. The model is trained using supervised learning with paired routine-dose clinical non-contrast head CT images as training targets and simulated low-dose (25%) images as training inputs. One hundred unique de-identified clinical exams were used for training, ten for validation, and ten for testing. Visual comparisons and contrast measurements of ZIRCON revealed that thinner slices and the smooth-kernel loss function improved gray-white matter contrast. Combined with lower noise, this increased visibility of small soft-tissue features that would be otherwise impaired by partial volume averaging or noise. Line profile analysis showed that ZIRCON images largely retained sharpness compared to the sharp-kernel input images. ZIRCON combined desirable image quality properties of both smooth and sharp input kernels into a single, thin, low-noise series suitable for both brain and skull imaging.

Ballistic Limit of UHMWPE Composite Armor under Impact of Ogive-Nose Projectile.

The ballistic response of armor has been widely used to evaluate its feasibility and advantages as a protective structure. To obtain the ballistic performance and ballistic limitations of composite armor, a type of ultra-high molecular weight polyethylene (UHMWPE) composite armor is designed, which is composed of UHMWPE laminates and steel face sheets of Q235. The total thickness of the armor is 53 mm, with an in-plane dimension of 300 mm × 300 mm. Then, an experimental study of the ballistic impact response of composite armor subject to a typical ogive-nose projectile was carried out. In the velocity range of 501.1 to 1026.1 m/s, the 14.5 mm caliber armor-piercing projectile could penetrate through the composite armor. At the velocity of 433.3 m/s, the A-P projectile was embedded in the armor, leaving a bulge mark on the back sheet. Therefore, 467.2 m/s is taken as the ballistic limit of the armor under the impact of the ogive-nose projectile. In addition, a corresponding numerical simulation model is also established to predict the ballistic limit of the projectile. The numerical predictions are consistent with the experimental results. The ballistic limit obtained from the numerical simulation results is 500 m/s, which is acceptable with a relative error of 7.02%. The failure mechanism of the composite armor is also obtained. Petaling is the main dominant failure mode for both face sheets, while delamination and shear failure dominate the penetration process of UHMWPE laminates. Finally, the perforation mechanism of composite armor under the impact of an A-P projectile is analyzed with theoretical models to predict the residual velocity, the work performed during the perforation, and the resisting stress of σs in the cavity-expansion model. The experimental and numerical simulation results can provide necessary data in the analysis of the composite structure's dynamic response under the impact of sharp head penetrators. The research results present the ballistic performance, failure mechanism, and ballistic limit of the composite armor under the impact of a typical ogive-nose projectile, which can be significant in the design of composite armor in the areas of ship shield, fortifications protection, and bulletproof structures against threats from sharp head penetrators.

Shock-tube studies of single- and quasi-single-mode perturbation growth in Richtmyer–Meshkov flows with reshock

The Richtmyer–Meshkov instability of heavy/light single-mode (SM), trapezoid (TR) and sawtooth (ST) interfaces is studied experimentally by considering the reshock. The TR and ST interfaces can be expanded into Fourier series with a dominant fundamental mode and more high-order modes, recognized as quasi-single-mode ones. In experiments, the distorted interfaces at the time of first reshock arrival develop in the weakly nonlinear stage, ensuring an approximate single-scale function of evolving interface. The results show an evident memory of initial interface shapes: the bubbles and spikes of ST interface after reshock mainly develop in the streamwise direction with sharp heads, while the counterparts of TR interface tend to grow in the spanwise direction. The influences of high-order modes are amplified by the reshock, resulting in significant interface shape dependence of mixing width growths. The amplitude superposition of major odd-order modes promotes the growth rates of mixing widths for the SM and ST cases, different from the TR one. The ST interface has larger mixing width growth rates in comparison with the SM interface, since high-order modes play a great role in promoting the increase of ST amplitudes, while the TR interface has a relatively small one. The linear and nonlinear mixing width growths of SM, TR and ST interfaces before and after reshock are further analysed theoretically, indicating that the fundamental mode still has a predominant influence on the interface evolution after reshock, and the growth behaviours exhibit strong similarities to those for the singly shocked cases.

Characteristics of productive broodstock based on body length and gonad histology of eel (Monopterus albus) in Semarang

The purpose of this study is to describe the characteristics of productive broodstock based on body length and histological gonad description of eels in Semarang. Samples of catched eels in various sizes, each measured its length and weight, determined its sex, recorded morphologically and made microtechnic histological description of gonads. Based on description of gonad hyostology, the eels body length is 28-32 cm for female and consists of egg cells set, which are in 32-36 cm is intersex, the egg cell is decreased sperm cells begin to develop and those are in 37-45 cm. Based on IKG eels obtained in four subdistricts, the egg size cannot be measured because they are in 1.7 to 2.3 mm. Based on gonads microscopic view and visual body length at TKG II, TKG III and IV consisted of eggs and sperm. While eels IKG obtained the most are 25 eels in IKG class 2.829943-3.829943. Conclusion of this research showed that productive female eels have an average body length of 26 - 34 cm with a morphology characteristic sharp head, greenish skin color on the back and yellowish white on the abdomen. Productive male eels have a body length in 54 - 60 cm with a morphological characteristic is greenish brown back, brownish yellow belly, large head and nape size, slightly short tail and blunt ends.

Beer stein blast to the head a rare case of combined blunt and sharp force trauma

Cases of combined blunt and sharp force trauma to the head caused by one striking tool are rare. When beer steins are used as an assault weapon, they can cause blunt traumas upon initial contact phase. If the impact force exceeds the mechanical stability of the beer stein, it breaks into several sharp-edged pieces, which then can cause sharp force trauma injuries due to the interaction between the head and the stein fragments.We present a case of a 43-year old man, who suffered from blunt and sharp force head traumas due to one single blow with a 1-l beer stein. A forensic-biomechanical analysis of the event, together with witness testimony evaluation and experimental comparison helped to reconstruct the most probable chain of events. Based on these findings as well as on the medical diagnoses and treatment, the assault was assessed as a nonacute life-threatening, but potentially fatal offence. The case was indicted as grievous bodily harm.

Role of tyramine in calcium dynamics of GABAergic neurons and escape behavior in Caenorhabditis elegans

BackgroundTyramine, known as a “trace amine” in mammals, modulates a wide range of behavior in invertebrates; however, the underlying cellular and circuit mechanisms are not well understood. In the nematode Caenorhabditis elegans (C. elegans), tyramine affects key behaviors, including foraging, feeding, and escape responses. The touch-evoked backward escape response is often coupled with a sharp omega turn that allows the animal to navigate away in the opposite direction. Previous studies have showed that a metabotropic tyramine receptor, SER-2, in GABAergic body motor neurons controls deep body bending in omega turns. In this study, we focused on the role of tyramine in GABAergic head motor neurons. Our goal is to understand the mechanism by which tyraminergic signaling alters neural circuit activity to control escape behavior.ResultsUsing calcium imaging in freely moving C. elegans, we found that GABAergic RME motor neurons in the head had high calcium levels during forward locomotion but low calcium levels during spontaneous and evoked backward locomotion. This calcium decrease was also observed during the omega turn. Mutant analyses showed that tbh-1 mutants lacking only octopamine had normal calcium responses, whereas tdc-1 mutants lacking both tyramine and octopamine did not exhibit the calcium decrease in RME. This neuromodulation was mediated by SER-2. Moreover, tyraminergic RIM neuron activity was negatively correlated with RME activity in the directional switch from forward to backward locomotion. These results indicate that tyramine released from RIM inhibits RME via SER-2 signaling. The omega turn is initiated by a sharp head bend when the animal reinitiates forward movement. Interestingly, ser-2 mutants exhibited shallow head bends and often failed to execute deep-angle omega turns. The behavioral defect and the abnormal calcium response in ser-2 mutants could be rescued by SER-2 expression in RME. These results suggest that tyraminergic inhibition of RME is involved in the control of omega turns.ConclusionWe demonstrate that endogenous tyramine downregulates calcium levels in GABAergic RME motor neurons in the head via the tyramine receptor SER-2 during backward locomotion and omega turns. Our data suggest that this neuromodulation allows deep head bending during omega turns and plays a role in the escape behavior in C. elegans.

Experimental Study of the Multiphase Flow of Sand, Viscous Oil, and Gas in a Horizontal Pipe

SummaryThis study provides horizontal-pipe pressure-drop and liquid-holdup measurements for three-phase flow of sand, viscous oil, and gas with a focus on slug flow (SL). We developed a correlation for predicting the liquid holdup and dimensionless pressure gradient in the presence of solids during SL.A multiphase-flow-loop facility with 1.5-in. (0.0381m) Schedule 80 polyvinyl chloride (PVC) pipes was designed and constructed to flow viscous oils ranging from 150 to 218 cp (0.15 to 0.218 Pa·s). Two-phase (221) and three-phase (88) data points were collected. A progressing cavity pump (PCP) was used to pump the complex mixture from a double-walled steel tank. Compressed air was used as the gas phase and 0 to 1 wt% of 180-µm diameter sand (test-section concentrations) was added to the flow. The facility had a clear test section for flow-pattern visualization and photography. Equipment issues and operational difficulties in the setup were identified during initial tests and rectified. Oil- and gas-flow rates, differential and absolute pressures, liquid holdup (both with and without the presence of solids), and fluid temperatures were measured, and flow-pattern observations were photographed. Gas and viscous-oil superficial velocities ranged from 0.1 to 10 m/s and from 0.1 to 1 m/s, respectively.We validated the setup by comparing actual single-phase liquid-pressure-drop measurements to an analytical expression for computing the pressure drop during single-phase viscous-oil flow. Sand was introduced into the system thereafter. We found that the presence of sand did not shift the flow-pattern boundaries appreciably and SL was the most commonly encountered flow pattern. As such, we focused on the SL region. Slow-motion photography and videography revealed that the presence of sand disrupted the sharp head and tail profiles in the liquid-slug body. Regression analysis using the observed data revealed that for SL of viscous oil and gas, the most-important dimensionless groups affecting both the holdup and the dimensionless pressure gradient are the fluid-velocity numbers and the Froude number. For three-phase SL of sand, viscous oil, and gas, the most-important dimensionless groups for affecting holdup in the presence of solids are the fluid velocity, Reynolds number, and Froude number in addition to the pipe-diameter number and the sand fraction in the flow stream. For dimensionless pressure gradient, the most-important dimensionless groups are the fluid-velocity numbers, the Reynolds and Froude numbers, and the input-liquid fraction.Slug-unit length was also measured, and the data were matched with an existing correlation. We also detailed the effect of sand on pattern behavior in each of the commonly observed horizontal-pipe multiphase-flow patterns using videography.To the best of our knowledge, this is the first recorded attempt at measuring pressure drop and liquid holdup in the presence of solids for the horizontal multiphase flow of sand, viscous oil, and gas. This work provides laboratory data/models that can support the characterization of the pressure drop and flow patterns experienced in horizontal wells completed using the process of cold heavy-oil production with sand (CHOPS) and other viscous-oil-producing wells.

MantisBot successfully mimics prey tracking

The praying mantis is a notorious insect, known for its calm, motionless stance while waiting for prey to draw near, followed by a swift and powerful strike. Mantises track moving prey using rapid turning head movements to keep their target in the foveal region of the eyes, where the highest resolution images are produced. Though much is known about insect motion and control, exactly how mantises use visual information to produce these sharp head turns remains unclear. What makes this insect especially interesting is that numerous studies have found that once a turn is initiated, it cannot be stopped – meaning that the mantis must predict the future position of its prey. So, what information does the brain send to the nerve clusters controlling locomotion in order to produce these precise movements?This is the question that an interdisciplinary team of researchers attempted to answer with their mantis-inspired robot, MantisBot. Based on previous studies of praying mantis head movements and insect locomotion in the literature, the team – led by Nicholas Szczecinski from Case Western Reserve University in Ohio, USA – hypothesised that commands to the nerve centres that control locomotion are relatively simple. To test this, they designed a simple nervous network with commands inspired from those biological results, and incorporated it into MantisBot, a 13.3:1 scale robot model of a praying mantis. Based on information provided by the ‘eyes’ – five solar cells arranged around the front of the head – a bioinspired brain-like controller gave simple instructions to the unit controlling the robot's movements: either move or stand still, and which direction to orient the body.To test how well the proposed network directed the robot, the team shone a 1600 lumen LED at it to simulate prey; the difference in voltage of the solar cells told the robot which direction the prey was in. If the prey moved outside a 20 deg cone from the centre of its vision, the controller told the robot to move its head, and if it moved even further (30 deg outside), the robot also used its body and legs too, just like real praying mantises do. But could it track prey accurately?MantisBot's control network was a success, allowing the robot to track prey to within 30 deg of its centre of vision, even when moving its legs and body. Switching direction mid-step was no problem either, and the robot successfully used its legs to help rotate its body while standing still. The robot's high accuracy in tracking prey demonstrates that simple commands – which direction, and whether or not to move – are capable of producing tracking behaviour comparable to that of the praying mantis, and provides plausible evidence that the information sent to the animal's own locomotion control centre could be just as simple.Bioinspired robotic models are not just great precursors to more advanced robots; studies like this demonstrate that they can also supply meaningful feedback, helping us to understand the underlying biology to answer questions that current biological experiments cannot address. Continuing such interdisciplinary work is therefore essential for both fields to progress, and could potentially provide answers to many biological conundrums.

Shunt Surgery in Idiopathic Intracranial Hypertension Aided by Electromagnetic Navigation

Background: Idiopathic intracranial hypertension (IIH) is characterized by increased cerebrospinal fluid (CSF) pressure and normal or slit ventricles. Lumboperitoneal shunting had been favored by many investigators for CSF diversion in IIH for decades; however, it has been associated with various side effects. Because of the small ventricular size adequate positioning of a ventricular catheter is challenging. Objectives: Here, we investigated the usefulness of electromagnetic (EM)-guided ventricular catheter placement for ventriculoperitoneal shunting in IIH. Methods: Eighteen patients with IIH were included in this study. The age of patients ranged from 5 to 58 years at the time of surgery (mean age: 31.8 years; median: 29 years). There were 2 children (5 and 11 years old) and 16 adults. Inclusion criteria for the study were an established clinical diagnosis of IIH, lack of improvement with medication, and the presence of small ventricles. In all patients EM-navigated placement of the ventricular catheter was performed using real-time tracking of the catheter tip for exact positioning close to the foramen of Monro. Postoperative CT scans were correlated with intraoperative screen shots to validate the position of the catheter. Results: In all patients EM-navigated ventricular catheter placement was achieved with a single pass. There were no intraoperative or postoperative complications. Postoperative imaging confirmed satisfactory positioning of the ventricular catheter. No proximal shunt failure was observed during the follow-up at a mean of 41.5 months (range: 7-90 months, median: 40.5 months). Conclusions: EM-navigated ventricular catheter placement in shunting for IIH is a safe and straightforward technique. It obviates the need for sharp head fixation, the head of the patient can be moved during surgery, and it may reduce the revision rate during follow-up.

Real-time imaging of moving living objects using a compact terahertz scanner

In this study, we design a compact terahertz (THz) reflection scanner with a scan rate of 20 frames/s. This scanner is based on a benzocyclobutene-embedded InGaAs Schottky barrier diode detector having a maximum responsivity of 300 V/W at 250 GHz and a minimum noise equivalent power of 38 pW/. With this scanner, details such as sharp head and tail and wrinkled segments in a moving caterpillar are observed. The thin and thick parts of the moving caterpillar that are presented in light gray and dark gray, respectively, on the gray scale are also well distinguished.

アルミニウム合金板への尖頭薄板飛翔体の衝突・貫通現象

Experiments and simulations on sharp head projectile impact to circular plates made of aluminum alloy 2024-T3 were carried out. The crack limit velocity, perforation limit velocity and deformation of the plates were measured. These experimental results were compared with simulations using material properties experimentally obtained. The fracture mechanisms of impact point were discussed.

Endoscopic intracranial surgery enhanced by electromagnetic-guided neuronavigation in children.

Navigated intracranial endoscopy with conventional technique usually requires sharp head fixation. In children, especially in those younger than 1 year of age and in older children with thin skulls due to chronic hydrocephalus, sharp head fixation is not possible. Here, we studied the feasibility, safety, and accuracy of electromagnetic (EM)-navigated endoscopy in a series of children, obviating the need of sharp head fixation. Seventeen children (ten boys, seven girls) between 12 days and 16.8 years (mean age 4.3 years; median 14 months) underwent EM-navigated intracranial endoscopic surgery based on 3D MR imaging of the head. Inclusion criteria for the study were intraventricular cysts, arachnoid cysts, aqueduct stenosis for endoscopic third ventriculostomy (ETV) with distorted ventricular anatomy, the need of biopsy in intraventricular tumors, and multiloculated hydrocephalus. A total of 22 endoscopic procedures were performed. Patients were registered for navigation by surface rendering in the supine position. After confirming accuracy, they were repositioned for endoscopic surgery with the head fixed slightly on a horseshoe headholder. EM navigation was performed using a flexible stylet introduced into the working channel of a rigid endoscope. Neuronavigation accuracy was checked for deviations measured in millimeters on screenshots after the referencing procedure and during surgery in the coronal (z = vertical), axial (x = mediolateral), and sagittal (y = anteroposterior) planes. EM-navigated endoscopy was feasible and safe. In all 17 patients, the aim of endoscopic surgery was achieved, except in one case in which a hemorrhage occurred, blurring visibility, and we proceeded with open surgery without complications for the patient. Navigation accuracy for extracranial markers such as the tragus, bregma, and nasion ranged between 1 and 2.5 mm. Accuracy for fixed anatomical structures like the optic nerve or the carotid artery varied between 2 and 4 mm, while there was a broader variance of accuracy at the target point of the cyst itself ranging between 2 and 9 mm. EM-navigated endoscopy in children is a safe and useful technique enhancing endoscopic intracranial surgery and obviating the need of sharp head fixation. It is a good alternative to the common opto-electric navigation system in this age group.

Cerebral Perfusion Pressure and Intracranial Pressure in Traumatic Brain Injury

Nearly 300,000 children and adults are hospitalized annually with traumatic brain injury (TBI) and monitored for many vital signs, including intracranial pressure (ICP) and cerebral perfusion pressure (CPP). Nurses use these monitored values to infer the risk of secondary brain injury. The purpose of this chapter is to review nursing research on the monitoring of ICP and CPP in TBI. In this context, nursing research is defined as the research conducted by nurse investigators or research about the variables ICP and CPP that pertains to the nursing care of the TBI patient, adult or child. A modified systematic review of the literature indicated that, except for sharp head rotation and prone positioning, there are no body positions or nursing activities that uniformly or nearly uniformly result in clinically relevant ICP increase or decrease. In the smaller number of studies in which CPP is also measured, there are few changes in CPP since arterial blood pressure generally increases along with ICP. Considerable individual variation occurs in controlled studies, suggesting that clinicians need to pay close attention to the cerebrodynamic responses of each patient to any care maneuver. We recommend that future research regarding nursing care and ICP/CPP in TBI patients needs to have a more integrated approach, examining comprehensive care in relation to short- and long-term outcomes and incorporating multimodality monitoring. Intervention trials of care aspects within nursing control, such as the reduction of environmental noise, early mobilization, and reduction of complications of immobility, are all sorely needed.

The cross breeding and genetic analysis of hybrids of Larimichthys crocea(♀)and Nibea miichthioides(♂)

To understand the feasibility of cross breeding between Larimichthys crocea ♀ and Nibea miichthioides ♂,two hybrid families were built(LN1 and LN2).Ploidy of F1 hybrids was identified.Moreover,ten microsatellite loci were used for genetic relationship analysis between F1 hybrids and their parents.The result showed that L.crocea(♀)and N.miichthioides(♂)can be successfully crossed and hybrid offspring of normal survival were produced.Survival rate of hybrid offspring at the age of 45 days post hatch reached about 30%.However,fertilization rate(29.0%,32.6%)and hatching rate(75.0%,76.7%)of two hybrid families were significantly lower than those in large yellow croaker families(P0.05).Appearance of juvenile hybrid fish is visibly different from those of large yellow croaker,which has characteristics of both parents:slender body,sharp blunt head and their body sides are covered with black-brown spots.The results of DNA relative content investigation and genetic relationship analysis demonstrated that more than 90% of the hybrid offspring were hybrid diploid,in addition,a small number of those were hybrid triploid and gynogenesis diploid.Till the age of 45 days,growth rate of both hybrid diploid and hybrid triploid was slower than that of large yellow croaker.These findings will provide reference for exploitation and management of F1 hybrids of L.crocea(♀)and N.miichthioides(♂).

Electromagnetic-guided neuronavigation for safe placement of intraventricular catheters in pediatric neurosurgery

Ventricular catheter shunt malfunction is the most common reason for shunt revision. Optimal ventricular catheter placement can be exceedingly difficult in patients with small ventricles or abnormal ventricular anatomy. Particularly in children and in premature infants with small head size, satisfactory positioning of the ventricular catheter can be a challenge. Navigation with electromagnetic tracking technology is an attractive and innovative therapeutic option. In this study, the authors demonstrate the advantages of using this technology for shunt placement in children. Twenty-six children ranging in age from 4 days to 14 years (mean 3.8 years) with hydrocephalus and difficult ventricular anatomy or slit ventricles underwent electromagnetic-guided neuronavigated intraventricular catheter placement in a total of 29 procedures. The single-coil technology allows one to use flexible instruments, in this case the ventricular catheter stylet, to be tracked at the tip. Head movement during the operative procedure is possible without loss of navigation precision. The intraoperative catheter placement documented by screenshots correlated exactly with the position on the postoperative CT scan. There was no need for repeated ventricular punctures. There were no operative complications. Postoperatively, all children had accurate shunt placement. The overall shunt failure rate in our group was 15%, including 3 shunt infections (after 1 month, 5 months, and 10 months) requiring operative revision and 1 distal shunt failure. There were no proximal shunt malfunctions during follow-up (mean 23.5 months). The electromagnetic-guided neuronavigation system enables safe and optimal catheter placement, especially in children and premature infants, alleviating the need for repeated cannulation attempts for ventricular puncture. In contrast to stereotactic techniques and conventional neuronavigation, there is no need for sharp head fixation using a Mayfield clamp. This technique may present the possibility of reducing proximal shunt failure rates and costs for hydrocephalus treatment in this age cohort.

Internal Structure of Planar Electrochemical Doping Fronts in Organic Semiconductors

The internal structure of electrochemical doping fronts in organic semiconductors is investigated using an extended drift-diffusion model for ions, electrons, and holes. The model also involves the injection barriers for electrons and holes in the partially doped regions in the form of the Nernst equation, together with a strong dependence of the electron and hole mobility on concentrations. It is shown that the internal structure of the doping fronts is controlled by a balance between the diffusion and mobility processes. The asymptotic behavior of the concentrations and the electric field is studied analytically inside the doping fronts. The numerical solution for the front structure confirms the most important findings of the analytical theory: a sharp head of the front in the undoped region, a smooth relaxation tail in the doped region, and a plateau at the critical point of transition from doped to undoped regions. The theoretically predicted complex structure of the doping fronts is in agreement with the previous experimental data. The acceleration of the p- and n-fronts toward each other in light-emitting electrochemical cells is described. The theoretical predictions for the planar front acceleration are in a good quantitative agreement with the experimental measurements for the backside of the curved doping fronts.

Risk Factors for Neurosensory Disturbance After Bilateral Sagittal Split Osteotomy Based on Position of Mandibular Canal and Morphology of Mandibular Angle

The aim of the present study was to evaluate the potential morphologic risk factors for postoperative neurosensory disturbance (NSD) after bilateral sagittal split osteotomy. The study subjects were 30 skeletal Class III patients (9 males and 21 females), with a mean age of 22.0 years (range, 16-39 years). All patients underwent bilateral sagittal split osteotomy for setback to correct mandibular prognathism. The bone marrow space between the outer mandibular canal and the lateral cortex of the ramus was measured on transaxial computed tomography images, and the length at the mandibular angle between the retromolar and gonion was measured on the lateral cephalograms. The NSD was tested bilaterally using discrimination to touch with the sharp head of a mechanical probe. Each patient was evaluated at 1, 3, and 6 months postoperatively. The median bone marrow space was 1.96 mm (range, 0-4.5 mm), and median length of the mandibular angle was 30.93 mm (range, 23-37 mm). Neurosensory disturbance was present on 15 sides (25.0%) at 1 month postoperatively, 9 sides (15.0%) at 3 months postoperatively, and 7 sides (11.7%) at 6 months postoperatively. The difference in the incidence of NSD with a small bone marrow space and a long mandibular angle from that with a large bone marrow space and short mandibular angle was highly statistically significant (P = .006 and P < .01, respectively). The frequency of NSD after bilateral sagittal split osteotomy in Class III cases was dependent not only on the position of mandibular canal, but also on the length of the mandibular angle. A lateral course of the mandibular canal and a long mandibular angle appeared to result in a high risk of injury to the inferior alveolar nerve, resulting in NSD owing to a compromised splitting procedure.

Micro RNAs and cancer.

The biological processes that lead to cancer and the recent surge of discoveries relating the over-expression of specific micro RNAs (miRNAs) to cancer prognosis, featured prominently in the 101st Annual AACR meeting programme. MiRNAs are small molecules that regulate gene expression. Initially it was unclear whether altered miRNA expression observed in cancer was a cause or consequence of malignant transformation however numerous studies clearly demonstrated that widespread reduction in miRNA expression does, indeed, promote tumorigenesis. “The science of miRNAs and related small RNAs will continue to generate new insights into cancer and possible future treatments” said Nobel Laureate Phillip A. Sharp head of the Koch Institute for Integrative Cancer Research at the Massachusetts Institute of Technology, Cambridge, at a press conference presenting some of the miRNAs related talks at the recent 101st AACR conference in Washington DC. One of the presenters at this conference, Sumaiyah Rehman, discussed the effect of a specific microRNA, Mir-21, on trastuzumab (Herceptin) therapy. For Her2/neu positive breast cancer patients, the standard treatment is trastuzumab + chemotherapy but approximately 35% of patients will develop resistance to treatment. Rehman,thinks that the loss of a specific protein PTEN, a tumour suppressor is a key player in the resistance in this group of breast cancers. As miR-21 targets the PTEN mRNA leading to PTEN protein downregulation, the researchers thought that the increased levels of Mir-21 and the reduced levels of PTEN could result in the resistence to trastuzumab. They tested their hypothesis in cell lines which overexpress HER-2 and found that cells with higher levels of Mir-21 had reduced levels of PTEN and were much more resistant to trastuzumab than control cells. These results are supported by results from the clinic which indicated that in Her-2 positive breast cancer patients with higher levels of Mir-21 had a poorer response to Herceptin which also correlated with disease progression. Eva Hernando also presented results from her laboratory in which they have identified a group of miRNAs specifically associated with brain metastasis from melanoma. Brain matasteses occur in 40%–60% of melanoma patients and the there is no effective treatment. They also found that this group of miRNAs could be already identified in the primary tumour and so identification of this profile at the time of diagnosis may help in deciding effective treatments for these more aggressive tumour types. Also targets of these miRNAs could represent novel therapeutic targets. Liselle Bovell also discussed data relating a higher expression of a group of miRNAs and poorer prognosis in colorectal cancer patients. It is now clear that these tiny molecules can have significant effects in cancer progression. The results presented at the recent AACR meeting in Washington represent just a small fraction of the ongoing studies being carried out to try to better understand the biological pathways that are regulated by these tiny molecules and how the information gained can be used in the clinic to develop potentially effective treatments.

Variability of Cross-shelf Penetrating Fronts in the East China Sea

Images of 8-day mean chlorophyll- a concentrations of the Moderate Resolution Imaging Spectroradiometer (MODIS) onboard of Aqua Satellite from 2002 to 2007 and of the Sea-viewing Wide Field-of-view Sensor (SeaWiFS) satellite from 1998 to 2007 are used to study the variability of the cross-shelf penetrating fronts (CPFs) in the East China Sea. The analysis suggests that the generation of the CPFs has strong seasonal-to-interannual variations, with more CPFs in summer and winter than in spring and fall. Each CPF lasts for a few days to a month. The majority of the fronts are triangle-shaped with their broad bases nearby the coast and their sharp heads penetrating into the middle shelf. There are over 40 CPFs with penetrating distances exceeding 100 km over the East China Sea during the past 10 years of the satellite era, with the maximum ones reaching the Kuroshio at the edge of the continental shelf. Of all the low cloud scenes of the satellite images, more than 25% contain at least one CPF. The high-frequency occurrence of the CPFs suggests that the CPFs play an important role in cross-shelf transport of heat, effluent, and land-derived materials in the East China Sea. The generation of the CPF is found to be influenced by winds and by intrinsic oceanic variability. In particular, the collision of wind-forced coastal jet with the Taiwan Warm Current is suggested as one of the mechanisms that generate the CPFs in the East China Sea.