End Of Segment Research Articles

Finite Element Analysis of a Bionate Ring-Shaped Customized Lumbar Disc Nucleus Prosthesis.

Study design: Biomechanical study of a nucleus replacement with a finite element model. Objective: To validate a Bionate 80A ring-shaped nucleus replacement. Methods: The ANSYS lumbar spine model made from lumbar spine X-rays and magnetic resonance images obtained from cadaveric spine specimens were used. All materials were assumed homogeneous, isotropic, and linearly elastic. We studied three options: intact spine, nucleotomy, and nucleus implant. Two loading conditions were evaluated at L3-L4, L4-L5, and L5-S1 discs: a 1000 N axial compression load and this load after the addition of 8 Nm flexion moment in the sagittal plane plus 8 Nm axial rotation torque. Results: Maximum nucleus implant axial compression stresses in the range of 16–34 MPa and tensile stress in the range of 5–16 MPa, below Bionate 80A resistance were obtained. Therefore, there is little risk of permanent implant deformation or severe damage under normal loading conditions. Nucleotomy increased segment mobility, zygapophyseal joint and end plate pressures, and annulus stresses and strains. All these parameters were restored satisfactorily by nucleus replacement but never reached the intact status. In addition, annulus stresses and strains were lower with the nucleus implant than in the intact spine under axial compression and higher under complex loading conditions. Conclusions: Under normal loading conditions, there is a negligible risk of nucleus replacement, permanent deformation or severe damage. Nucleotomy increased segmental mobility, zygapophyseal joint pressures, and annulus stresses and strains. Nucleus replacement restored segmental mobility and zygapophyseal joint pressures close to the intact spine. End plate pressures were similar for the intact and nucleus implant conditions under both loading modes. Manufacturing customized nucleus implants is considered feasible, as satisfactory biomechanical performance is confirmed.

Double F-P Interference Optical Fiber High Temperature Gas Pressure Sensor Based on Suspended Core Fiber

A compact and simple double F-P interference optical fiber optic gas pressure sensor based on suspended core structure is proposed and demonstrated. The sensor is formed by splicing a Section of thin-walled grapefruit photonic crystal fiber (G-PCF) with single-mode fiber (SMF). By adjusting the special fusion parameters, a short air-cavity region is formed in the G-PCF next to the splicing point with the SMF segment, and the other end of the G-PCF segment is open to the atmosphere. The output interference spectrum of the sensor comprises of two spectral parameters that have different sensitivities to temperature and gas pressure. One of them is the wideband envelope that is associated with the air-cavity and it is only sensitive to the gas pressure but insensitive to the change of ambient temperature. This property is particularly useful for addressing the complex temperature-pressure cross sensitivity of both spectral parameters. The research findings indicate that the sensor can perform an accurate measurement for gas pressure in dynamic range of 0-1.0 MPa under the high temperature condition up to 500 °C.

Partial Eruption, Confinement, and Twist Buildup and Release of a Double-decker Filament

Abstract We investigate the failed partial eruption of a filament system in NOAA AR 12104 on 2014 July 5, using multiwavelength EUV, magnetogram, and Hα observations, as well as magnetic field modeling. The filament system consists of two almost co-spatial segments with different end points, both resembling a C shape. Following an ejection and a precursor flare related to flux cancellation, only the upper segment rises and then displays a prominent twisted structure, while rolling over toward its footpoints. The lower segment remains undisturbed, indicating that the system possesses a double-decker structure. The erupted segment ends up with a reverse-C shape, with material draining toward its footpoints, while losing its twist. Using the flux rope insertion method, we construct a model of the source region that qualitatively reproduces key elements of the observed evolution. At the eruption onset, the model consists of a flux rope atop a flux bundle with negligible twist, which is consistent with the observational interpretation that the filament possesses a double-decker structure. The flux rope reaches the critical height of the torus instability during its initial relaxation, while the lower flux bundle remains in stable equilibrium. The eruption terminates when the flux rope reaches a dome-shaped quasi-separatrix layer that is reminiscent of a magnetic fan surface, although no magnetic null is found. The flux rope is destroyed by reconnection with the confining overlying flux above the dome, transferring its twist in the process.

EFFECT OF AUTOGENOUS, NON-VASCULARIZED PERIOSTEUM TRANSPLANTATION ON ALLOGRAFT BONE GRAFTING FOR LARGE CORTICAL LOAD-BEARING BONE DEFECT – A RABBIT MODEL

Segmental bone allografts are widely used in managing large cortical bone defects. To improve host-graft union, the effect of allograft on a large cortical tibial bone defect augmented with a non-vascularized periosteal flap was studied. Twelve mature Australian white rabbits (Oryctolagus cuniculus) were divided into intervention groups and a control group. Bone defects in the intervention groups were treated with segmental allografts wrapped with a non-vascularized periosteal flap. The control group was treated with allograft transplantation alone. Healing was evaluated at the end of the 2nd, 4th, and 6th weeks with plain radiographs, CT scan, and histology. In the intervention groups, the bony union was achieved at both ends of the allografts at the 4th to 6th weeks. Solid callus encasing the whole allograft segments at the end of the 6th week. In the control group, the union did not occur at both ends of the allograft segments even up to the end of the 6th week. No callus formation surrounding the allograft segments. Fragmentation and telescoping of the allograft segment into the medullary cavity of the host were observed. The use of autogenous, non-vascularized periosteal flap modified the healing process of allograft and maintained the integrity of the allograft.

Effects on root axes and resorption of simultaneous intrusion and retraction of maxillary central and lateral incisors using mini-implant supported three-piece burstone base arch: A prospective observational study

Prospective morphometric evaluation of the positional changes and root resorption of maxillary central and lateral incisors undergoing simultaneous intrusion and retraction (SIR) using mini-implant supported 3-piece Burstone base arch. Bracket head type mini-implants were inserted between the maxillary second premolar and first permanent molar. After maxillary canine retraction, SIR of maxillary incisors was begun using mini-implant supported 3-piece Burstone arch. A segmental CBCT was taken before and after SIR of the maxillary four incisors. Data collected were analysed using Paired t test, ANOVA test, independent sample t test and Pearson's correlation test. Sixteen patients of 17.9±1.94 years mean age with class II division 1 malocclusion, deep bite≥4mm and overjet 5-8mm were selected. All mini-implants showed good stability during treatment with no looseness. Increasing the vertical end of the anterior segment up to 10mm led to controlled tipping and partial bodily retraction of the maxillary central and lateral incisors. The centre of resistance (CRe) of the four maxillary incisors was retracted 2.38±0.77mm and intruded 2.76±1.0mm with a mean change in axial inclination of 9.76±3.45°. The mean amount of root resorption of the four incisors was 1.29±0.59mm over a mean period of 6.2 months. The mini-implant supported 3-piece Burstone base arch had a pronounced effect on SIR of flared maxillary incisors with clinically insignificant amount of root resorption.

Exploring the role of the body in communicating ironic stance

Performing and understanding conversational irony requires a complex management of multiple viewpoints. To communicate and negotiate these intricate viewpoint shifts, speakers (and addressees) often use nonverbal means (e.g. gaze shifts, shrugs, shifts in body orientation, hand gestures, etc.) next to verbal viewpoint strategies. In the present paper we zoom in on the perspective of the speaker and try to describe and quantify bodily behavior in ironic utterances compared to non-ironic ones. To this end, we use data from a video-corpus of three-party interactions with participants wearing mobile eye-tracking devices that allow for precise eye gaze data. Our results show that speakers display more of the multimodal resources under scrutiny in ironic cases compared to non-ironic cases. More specifically, the involvement of bodily resources is mainly manifested in the use of laughter, head movements and body repositionings. We further show how those resources cluster into certain multimodal packages, and how the exact timing of the bodily behavior is relevant (i.e. the gaze behavior at the end of an ironic segment differs most notably from the end of a non-ironic one). Next to a quantitative analysis of the resources used in ironic talk in interaction, we also illustrate our findings with qualitative descriptions of relevant examples.

The Intersection Between the Sternocleidomastoid and Splenius Capitis as the Anatomical Landmark to Facilitate Occipital Artery Harvest: A Retrospective Clinical Study

Occipital artery (OA)-posterior inferior cerebellar artery (PICA) bypass is a challenging procedure and is not frequently performed owing to the difficulty of OA harvest. To facilitate harvest, the intersection between the sternocleidomastoid and splenius capitis (the OA triangle) is used as the anatomical landmark to identify the OA segment that carries the highest risk of damage. This clinical study aimed to demonstrate efficacy and safety of OA harvest using this landmark. The study included 18 patients who underwent OA harvest using the OA triangle as a landmark for treatment of vertebral artery and PICA aneurysms. Patients were retrospectively evaluated for safety and patency of OA after harvest and OA-PICA bypass. Of 18 patients with ruptured and unruptured vertebral artery and PICA aneurysms, 13 (72.2%) underwent OA-PICA bypass and 5 (27.8%) did not undergo bypass. The OA was completely harvested without damage in all patients. After harvest, the OA was patent in 17 patients (94.4%) and was occluded in 1 patient owing to vasospasm; this patient then underwent recanalization resulting in good patency of the OA-PICA bypass. The patency rate of the OA-PICA bypass was 100%. The OA triangle, which is the anatomical landmark of the proximal end of the transitional segment of the OA, facilitated OA harvest using the distal-to-proximal harvest technique with safety and good patency. To the best of our knowledge, this is the first study of OA harvest in clinical cases.

Improved analysis method of neuromuscular junction in Drosophila larvae by transmission electron microscopy

The Drosophila neuromuscular junction is an excellent model for neuroscience research. However, the distribution of neuromuscular junctions is very diffuse, and it is not easy to accurately locate during ultrathin sectioning, which seriously interferes with the ultrastructural analysis under electron microscopy that only has a small field of view. Here, we reported an efficient method for acquiring the ultrastructural picture of neuromuscular junctions in Drosophila larva under electron microscopy. The procedure was as follows: first, the larval sample of body wall muscle was placed between the metal mesh and was dehydrated with alcohol and infiltrated with epoxy resin to prevent the sample from curling or bending, after it was dissected and fixed into thin slices. Second, the sample was embedded in resin into a flat sheet to facilitate the positioning of the muscles. Third, carefully and gradually remove the excess resin and the cuticle of the larvae, cut off both ends of the special body segment, and trim the excess specific muscles according to the recommended ratio of trimming muscles, which would reduce the workload exponentially. At last, the trimmed sample were prepared into serial about 1000 ultrathin sections that was about total 80 microns thickness, and 30–40 sections were gathered into a grid to stain with lead citrate and uranyl acetate. This method could also be applied to the other small and thin samples such as the Drosophila embryo, ventral nerve cord and brain.

Development and experimental validation of a partially buckling-restrained brace with dual-plate cores

A new partially buckling-restrained brace with dual-plate cores (DPBRB) was proposed in this paper to improve the flexural stiffness of an all-steel BRB with a plate core. The core member was composed of two identical and separated plates in parallel. The restraining member consisted of steel channels and steel plates that were assembled with high-strength bolts. The restraining member was located at the periphery of the core member to restrain the edge part of the outside and the inside plates in the core member. The restraining member can be reused and easily disassembled by removing the bolts, which effectively improves the utilization. The test results and numerical simulation indicated that all specimens presented stable energy dissipation capacities and low-cycle fatigue properties. The yield segments exhibited inwards buckling deformation, and the deformations at the ends were more evident than those in the middle. Insufficient stiffness of the end of the restraining member caused large deformation and fatigue fracture of the end of the yield segment. A new all-steel assembled restraining plate was provided. The calculation formula for the design length of the restraining member was given based on the results of finite element analysis.

Cavitation on top of collision breaks the cover of coronary plaques and triggers acute coronary syndrome

Abstract Background Coronary injuries are hypothesized to be caused by the cavitation phenomenon (explosion of air bubbles) which is seen frequently in industrial pipes. Based on hydraulics principles applied to the coronary circulation. during distal negative suctioning in diastole, if the coronary static pressure decreases below the vapor pressure (VP), bubbles will form. They explode when the coronary static pressure recovers > the VP during systole. These explosions create jet waves weakening and rupturing the cover of the coronary plaques, triggering acute coronary syndrome (ACS). How could these events be observed, recorded and compared? Methods Coronary angiograms of patients with ACS and stable coronary artery disease (CAD) (control) were selected. The arteries were recorded at 15 frames per second and saved in the electronic health records and reviewed image by image. After the index artery was completely filled with contrast, the following images showed the blood in white moving in on a background of black contrast. The flow could be laminar, turbulent (mixing of blood in white and contrast in black), antegrade or RETROGRADE (black column traveling backward). At the same time, an artificial intelligence (AI) program was used to detect and identify the flow. Results There were 104 patients with ACS enrolled and 20 patients with stable CAD as control. First, in the ACS group, 84 lesions (80%) were in the end of the proximal segment of the left anterior descending artery (LAD) and mid-segment of the right coronary artery (RCA). 20 lesions (19%) were at the distal RCA. Second, during diastole, 95% of the flow were laminar. The flow became turbulent at the beginning of systole. The turbulence was caused by the COLLISION of the antegrade flow (end of diastole) and the retrograde flow (at the beginning of systole). These collisions were seen in 95% at the location of vulnerable plaques of patients with ACS. In the control patients, there were only 2 cases (10%) with collision. Third, in the 20 patients with lesions at the distal RCA, the lesions were seen to be located at the areas of recirculating flow, at the ostium of the posterior descending artery (PDA) or proximal to the origin of the PDA. The cause of turbulence was most likely due to cavitation on top of collision. The cavitation happened because of continuous steady forward flow (of the PDA) in the myocardium during systole, while at the proximal RCA the blood flew forward more slowly. (Fig.1) The DSICREPANCY of velocities at the proximal and distal RCA allowed the formation of an empty gap (bubble of air). When the flow reversed during systole, this retrograde flow slammed on the bubble which collapsed violently, injured, ruptured the cover of the plaque and started ACS. Conclusions Rupture of bubbles (cavitation) on top of collision was most likely the cause of injury to the cover of vulnerable plaques, triggering ACS. Understanding the mechanism will help to better manage ACS. Funding Acknowledgement Type of funding sources: None. Cavity formation and collisionFormation of cavitation at the PDA

Protection of converter dominated MV microgrid using changes in current's phase angle

Converter interfaced distributed generations in a microgrid feed the modulated current of limited magnitude during fault conditions. The protection design and its operation are thus challenging due to limited fault current which is further reduced by Petersen coil grounding in medium-voltage (MV) level. This paper aims to address this challenge by developing a current-only directional relay algorithm for the protection of converter dominated MV microgrid with Petersen coil grounding. The relay's operating principle is based on the sign of the change in phase angle of the fault current with respect to the prefault which indicates the direction of fault. The negative and positive changes in current's phase angle determine the fault in forward and reverse direction, respectively. The tripping decision is derived by comparing the binary output of the relay at both ends of the line segment under protection. This requires a simple, flexible and low bandwidth communication channel. Both theoretical analyses and simulation studies have been performed on a typical distribution grid intended to be operated as microgrid. The proposed protection method is suitable for microgrid having the converters with and without reactive power support. Various operating conditions are evaluated, including bidirectional power flow, high resistance fault, different fault types, loading conditions and signals with noise.

Binding Sites and the Mechanism of Action of Propofol and a Photoreactive Analogue in Prokaryotic Voltage-Gated Sodium Channels

Propofol, one of the most commonly used intravenous general anesthetics, modulates neuronal function by interacting with ion channels. The mechanisms that link propofol binding to the modulation of distinct ion channel states, however, are not understood. To tackle this problem, we investigated the prokaryotic ancestors of eukaryotic voltage-gated Na+ channels (Navs) using unbiased photoaffinity labeling (PAL) with a diazirine derivative of propofol (AziPm), electrophysiological methods, and mutagenesis. AziPm inhibits Nav function in a manner that is indistinguishable from that of the parent compound by promoting activation-coupled inactivation. In several replicates (8/9) involving NaChBac and NavMs, we found adducts at residues located at the C-terminal end of the S4 voltage sensor, the S4-S5 linker, and the N-terminal end of the S5 segment. However, the non-inactivating mutant NaChBac-T220A yielded adducts that were different from those found in the wild-type counterpart, which suggested state-dependent changes at the binding site. Then, using molecular dynamics simulations to further elucidate the structural basis of Nav modulation by propofol, we show that the S4 voltage sensors and the S4-S5 linkers shape two distinct propofol binding sites in a conformation-dependent manner. Supporting the PAL and MD simulation results, we also found that Ala mutations of a subset of adducted residues have distinct effects on gating modulation of NaChBac and NavMs by propofol. The results of this study provide direct insights into the structural basis of the mechanism through which propofol binding promotes activation-coupled inactivation to inhibit Nav channel function.

Extrusive upper crust formation at slow-spreading ridges: Fault steering of lava flows

The structure of the oceanic upper volcanic crust is less understood at slow-spreading ridges than at faster ones. Its construction is dominated by pillow lavas, reflecting lower effusion rates than those at fast spreading ridges, where sheet and lobate flows are common and flow off-axis while thickening the extrusive volcanic layer. Based on optical and high-resolution bathymetry data from the Lucky Strike segment (Mid-Atlantic Ridge), we document a mode of volcanic emplacement that likely operates at some magmatically robust slow- and ultra-slow spreading ridge segments, in the presence of strong gradients in magma supply. In these settings, sheet flows may efficiently transport melt away from magmatically robust segment centers in the along-axis direction, steered by normal faults, and exploiting along-axis topographic gradients, with limited across-axis flow. Surface lineations of sheet lava flows tend to be subparallel to fault scarps and the overall segment orientation, and show whorls, well-developed lava channels with associated levees, and surface fold structures at flow fronts. This mode of lava emplacement transitions away from the segment center to pillow-dominated seafloor near the segment ends, associated often with hummocks and axial volcanic ridges. This results in local lava emplacement due to a melt supply that is lower than at the segment center. We propose that fault-steering of lava flows along-axis, limiting off-axis transport as observed at fast-spreading systems, may be common at both slow- and ultra-slow spreading ridges with significant along-axis changes in magma supply linked to topographic gradients. As a result, the nature and properties of the extrusive volcanic layer may vary significantly along axis owing to changes in the modes of volcanic emplacement, as transitions from sheet flows to pillow lavas may impact the porosity structure and hence the seismic properties of the extrusive layer in the oceanic upper crust.

Rarest of All – A Case of Cesarean Scar Ectopic Pregnancy in an Elderly Woman

One of the most common causes of mortality of females in the first trimester is ectopic pregnancy. Ectopic pregnancy can occur at different anatomic locations of which the fallopian tube is most common. Very rarely implantation of blastocyst can occur in the lower uterine segment at the site of the previous transverse cesarean section; this very rare type of ectopic pregnancy is known as cesarean scar pregnancy. Cesarean scar pregnancy is usually associated with the risk of uterine rupture leading to hemorrhage and hence diagnosis at an early stage and a proper management is necessary to avoid any serious complications. We present an interesting case of a 39-year-old elderly woman of G3P2 L2 who complained of amenorrhea for the past 7 weeks. Her urine tested positive for β-human chorionic gonadotropin, and she was further sent for antenatal ultrasound scan to confirm the pregnancy. On transvaginal ultrasound examination, there was a single gestational sac with yolk sac, fetal pole, and cardiac activity seen at the anterior end of the lower uterine segment near the old healed scar of the previous cesarean section corresponding to the gestational age of 6 weeks and 6 days. A diagnosis of cesarean scar ectopic pregnancy was made. The woman underwent a laparotomy with excision and termination of the pregnancy. Ectopic pregnancy of any location should be promptly diagnosed and adequately treated. In cases where transvaginal ultrasonography is inconclusive, magnetic resonance imaging is performed. Diagnosis is important to avoid any further complications and in young females to preserve fertility.

Biomechanical properties of the ex vivo porcine trachea: A benchmark for three-dimensional bioprinted airway replacements

PurposeCombining tissue engineering and three-dimensional (3D) printing may allow for the introduction of a living functional tracheal replacement graft. However, defining the biomechanical properties of the native trachea is a key prerequisite to clinical translation. To achieve this, we set out to define the rotation, axial stretch capacity, and positive intraluminal pressure capabilities for ex vivo porcine tracheas. Study designAnimal study. Materials and methodsSix full-length ex vivo porcine tracheas were bisected into 5.5 cm segments. Maximal positive intraluminal pressure was measured by sealing segment ends with custom designed 3D printed caps through which a pressure transducer was introduced. Axial stretch capacity and rotation were evaluated by stretching and rotating the segments along their axis between two clamps, respectively. ResultsSix segments were tested for axial lengthening and the average post-stretch length percentage was 148.92% (range 136.81–163.48%, 95% CI 153–143%). The mean amount of length gain achieved per cartilaginous ring was 7.82% (range 4.71–10.95%, 95% CI 6.3–9.35%). Four tracheal segments were tested for maximal positive intraluminal pressure, which was over 400 mmHg. Degree of rotation testing found that the tracheal segments easily transformed 180° in anterior-posterior bending, lateral bending, and axial rotational twisting. ConclusionsWe define several biomechanical properties of the ex vivo porcine trachea by reporting the rotation, axial stretch capacity, and positive intraluminal pressure capabilities. We hope that this will aid future work in the clinical translation of 3D bioprinted airway replacement grafts and ensure their compatibility with native tracheal properties.

Vascular Diameters as Predictive Factors of Recanalization Surgery Outcomes in Internal Carotid Artery Occlusion.

Background: Revascularization surgery sometimes can achieve recanalization in patients with internal carotid artery occlusion (ICAO). High-resolution vessel wall magnetic resonance imaging (HRVWI) is a feasible technique to give detailed characteristics of the vessel wall, which may help to identify patients that carry higher success rates and more suitable for revascularization surgery.Objective: To examine the association between HRVWI characteristics of ICAO and the success rate of revascularization surgery in ICAO patients.Methods: We conducted a retrospective analysis of 31 ICAO recanalization patients enrolled from October 2017 to May 2019. The clinical data of patients and lesions were collected and analyzed.Results: A total of 31 ICAO patients were enrolled in this study. No significant differences were found between recanalization success and recanalization failure groups with regard to occlusion length, distal end of the occluded segment, and the treatment applied. The ipsilateral-to-contralateral diameter ratios (I/C ratios) of C1 or C2 and the diameter of C7 were positively related to recanalization success. A two-factor predictive model was constructed, and the I/C ratio of C2 < 0.86 and the diameter of C7 < 1.75mm were separately assigned 1 point. The ICAO patients who scored 0, 1, or 2 points had a risk of 5.6% (1/18), 55.6% (5/9), or 100% (4/4) to fail in the recanalization.Conclusions: The I/C ratios of C1 or C2 and the diameter of C7 are predictive factors of a revascularization surgery success in ICAO patients. A risk stratification model involving C2 and C7 was constructed for future clinical applications.

Correlation Properties Of HRV During Marathon Racing In Recreational Runners: Potential Biomarker Of Organismic Demands

PURPOSE: Scant information exits regarding cardiovascular response and regulation in real-world endurance training/competition. Although there is data describing behavior of heart rate (HR) and HR variability (HRV) during actual events, the specific linear indexes studied have been less than optimal for assessment of real-time exercise intensity due to a lack of appreciable changes during exercise. In this context, non-linear HRV analysis is a promising approach for internal load monitoring of organismic demands related to external load markers such as intensity, cadence and duration., leading to insights in complex regulation during endurance exercise. The present study is the first to examine the influence of a marathon race on non-linear dynamics of HRV to assess its feasibility as a potential biomarker during endurance exercise. METHODS: Eleven male recreational runners performed a marathon race on an almost flat profile. During the race, HR time series was recorded continuously. HRV time-domain measurements and correlation properties using short-term scaling exponent alpha1 of Detrended Fluctuation Analysis (DFA-alpha1) were calculated. RESULTS: All runners achieved a mean total time of 3:10:22 ± 0:17:56 h:min:sec with a blood lactate concentration of 4.04 ± 1.12 mmol/l after finishing the race. Comparing the beginning to the end segment of the marathon race, significant increases could be found for km split time (p < .001, d = .934) and for HR (p = .010, d = .804). Significant decreases could be found for meanRR (p = .013, d = .798) and DFA-alpha1 (p = .003, d = 1.132). CONCLUSIONS: DFA-alpha1 showed wide dynamic range throughout the race consisting of both uncorrelated and anti-correlated values. Lactate was consistent with sustained high intensity exercise when measured at the end of the event. Despite the gradual slowing of km split times especially past the midpoint, DFA-alpha1 continued to fall to values seen in the highest intensity domain during incremental exercise testing in agreement with lactate assessment. Therefore, the discrepancy between the reduced running pace with that of the decline of DFA-alpha1, demonstrate the benefit of using this dimensionless HRV index as a potential biomarker of internal load during endurance exercise.

Isolated medial rectus muscle laceration after bird strike.

A 66 year-old male suffered globe trauma due to A bird, a German Desert Hawk, strike. At the first examination in the emergency ünit a few hours after the injury, the patient reported persistent horizontal diplopia. He had right conjunctival laceration, mild proptosis, subconjunctival hematoma, exotropia with no adduction. Magnetic Resonance Imaging (MRI) revealed that it was suggestive of laceration of the right medial rectus muscle, at about the junction of it's anterior and middle thirds. During surgery; initially, the lacerated proximal end of the distal segment was isolated. The proximal segment of the medial rectus muscle was then carefully dissected. The two lacerated ends were then joined with 6-0 polyglactin sutures. The day after surgery, there was no deviation and diplopia in all diagnostic gaze positions.

Hydrodynamic model of blood flow in major arteries pulsing in various modes.

Traditionally, the arteries in mammals are viewed as the tubes with elastic wall, whose elasticity could be slowly (during a minute) tuned to change its diameter thereby regulating regional blood supply. Recent findings showed that an artery is a much more sophisticated organ, which can change elasticity of vascular wall within a fraction of a second during a cardiac cycle due to activation of its smooth muscles manifested by generation of arterial action potentials. The rapid variations in elasticity of vascular wall resulted in three basic modes of arterial pulsing: passive, active, and intermediate. The latter is characterized by counteraction of dilation force of arterial pressure and the contractile one of smooth muscle in arterial wall, which can result in seemingly "rigid" artery of constant diameter. The prevalence of any of these forces results in active or passive pulsing modes. Existence of various pulsing modes raises the question of their effect on the main function of blood vessels, i.e., the transport of blood. The aim of this study is to assess the effect of various modes of arterial pulsing on hydraulic impedance of major arteries. The linearized Navier-Stokes equation was employed to develop a model of pulsatile flow of viscous incompressible fluid at small velocity via a conduit artery with the walls of variable or constant elasticity. An essential feature of the developed model is the shape of variable pressure drop applied to the ends of arterial segment, which simulates the real changes in arterial pressure during the heartbeat. Here, it is modeled by periodic (systolic) positive bell-shaped impulses with maxima corresponding to systolic arterial pressure, while the minimal plateau level refers to diastolic arterial pressure. The model assesses the changes in arterial hydraulic impedance during a cardiac cycle relatively to the stable level corresponding to constant blood flow driven by persistent pressure drop. Within intermediate variety of pulsing modes between the active and passive ones, the approximation of rigid arterial segment with infinite elasticity of arterial wall showed that hydraulic impedance in rigid artery is not constant due to inertial properties of the flowing blood. In passive pulsing mode characterized with constant elasticity of arterial wall, the diameter of artery changes in parallel with systolic pressure applied to the ends of arterial segment. At this, the overall change of hydraulic resistance is negative. In active pulsing mode, elasticity of arterial wall varies at different phase shifts relative to arterial pressure due to periodic contractions and relaxation of the smooth muscles in arterial wall. An important feature of active mode is possibility to decrease the hydraulic impedance during the front of arterial pressure. Various experimental modes of artery pulsing can be mathematically simulated. The passive and active modes of pulsing as well as a broad variety of intermediate pulsing modes with various phase shifts between arterial pressure and its diameter result in potency of the arteries to tune its performance in order to meet the regional circulatory requirements. The model showed that active arterial pulsing can diminish the arterial hydraulic impedance and contribute to the work needed for circulation thereby helping the pumping action of the heart.

Correlation Properties of Heart Rate Variability during a Marathon Race in Recreational Runners: Potential Biomarker of Complex Regulation during Endurance Exercise.

There is only very limited data examining cardiovascular responses in real-world endurance training/competition. The present study examines the influence of a marathon race on non-linear dynamics of heart rate (HR) variability (HRV). Eleven male recreational runners performed a self-paced marathon road race on an almost flat profile. During the race, heart rate and beat-to-beat (RR) intervals were recorded continuously. Besides HRV time-domain measurements, fractal correlation properties using short-term scaling exponent alpha1 of Detrended Fluctuation Analysis (DFA-alpha1) were calculated. The mean finishing time was 3:10:22 ± 0:17:56 h:min:s with a blood lactate concentration of 4.04 ± 1.12 mmol/L at the end of the race. Comparing the beginning to the end segment of the marathon race (Begin vs. End) significant increases could be found for km split time (p < .001, d = .934) and for HR (p = .010, d = .804). Significant decreases could be found for meanRR (p = .013, d = .798) and DFA-alpha1 (p = .003, d = 1.132). DFA-alpha1 showed an appropriate dynamic range throughout the race consisting of both uncorrelated and anti-correlated values. Lactate was consistent with sustained high intensity exercise when measured at the end of the event. Despite the runners slowing after halfway, DFA-alpha1 continued to fall to values seen in the highest intensity domain during incremental exercise testing in agreement with lactate assessment. Therefore, the discrepancy between the reduced running pace with that of the decline of DFA-alpha1, demonstrate the benefit of using this dimensionless HRV index as a biomarker of internal load during exercise over the course of a marathon race.