Lateral Core Research Articles

Visualization of inhomogeneities in Ti:Sapphire laser medium

This work presents innovative methods for visualizing inhomogeneities and stress distributions in Ti:Sa (titanium-doped sapphire) crystals, which are challenging to assess due to their birefringent nature. Two experimental approaches were developed: the first enables two-dimensional mapping of the Figure of Merit (FoM) and absorption at wavelengths of 532 nm, 780 nm, and 1550 nm, revealing variations in absorption across the crystal. The second experiment utilizes circularly polarized light and polarization imaging to detect internal stress and defects. The results demonstrate the successful visualization of lateral absorption, stress, and core features within the crystals, offering insights into their optical quality. These techniques provide new possibility for evaluation of laser materials, with significant implications for improving the manufacturing and selection processes of Ti:Sa crystals in advanced laser applications.

NXOpen-based human-computer interaction design system development for lateral core extraction mechanism of inclined guide pillar

NXOpen-based human-computer interaction design system development for lateral core extraction mechanism of inclined guide pillar

Autologous bone plug-sliding with core decompression and bone marrow aspirate concentrate application: a joint-preserving surgical technique for corticosteroid-induced osteonecrosis of femoral head.

This study aimed to describe a surgical procedure for the management of corticosteroid-induced osteonecrosis of the femoral head (ONFH) and report its clinical results. The technique included harvesting a bone plug from the lateral femoral neck, core decompression, and bone marrow aspirate concentrate (BMAC) application; the procedure was completed by press-fit insertion of the autologous bone plug in the debrided area. Autologous bone plug-sliding with core decompression and bone marrow concentrate aspirate application provides good clinical outcomes in the management of ONFH. A retrospective review was performed using records of patients operated on between October 2019 and June 2021. Only patients with Ficat-Arlet stage-2 ONFH, who underwent the procedure described, were included. Twenty- nine hips (18 patients) were included and evaluated clinically and radiologically. Clinical evaluation included the Harris hip score (HHS) and Visual analogue scale (VAS) for pain, while radiological evaluation included direct radiographs. The average age was 39.8 years (± 11.7, range: 24-65 years). The average follow-up was 13.5 months (± 3.4, range: 8-19 months). There were improvements in the VAS pain and Harris hip scores in all patients. Average HHS increased from 61.90 to 87.45 (p < 0.001), while the average VAS pain score decreased from 7.14 to 3.27 (p < 0.001). No complications were encountered in any of the patients during the follow-up. None of the patients had femoral head collapse on the latest radiograph or required total hip replacement. The combination of the novel autologous bone plug-sliding method with conventional regenerative methods is a successful treatment choice for ONFH.

Is lumbopelvic motor control associated with dynamic stability during gait, strength, and endurance of core musculatures?: The STROBE study.

Core stability has been described as the product of motor control and muscular capacity of the lumbopelvic-hip complex. Because of the wide range of functions of the lumbopelvic-hip complex, the gold standard for evaluating core stability remains controversial. The Sahrmann core stability test (SCST), used in conjunction with the stabilizer pressure biofeedback unit (PBU), is widely applied to objectively evaluate core stability as this pertains lumbopelvic motor control. However, the association between such control and other elements of core stability including core strength, endurance, and dynamic stability during gait has not been well-studied. We investigated the relationships among the ability to control the lumbopelvic complex, core strength and endurance, and gait parameters. We compared lateral core endurance, hip strengths, and gait parameters (lateral oscillation of the center of mass (COM), the single support time, and the peak ground reaction force) between good and poor core stability groups, as determined by the SCST. In addition, logistic regression analysis was used to determine whether other core stability measures correlated with the core stability status defined by the SCST. Only lateral oscillation of the COM during walking differed significantly between the good and poor core stability groups and was a significant predictor of SCST core stability status. Lumbopelvic motor control, (as defined by the SCST), affects dynamic stability during gait, but not to the strength or endurance of the core musculatures.

Association of Core Muscle Endurance with Weekly Workout Time, Speed, and the Symmetry of Frontal Core Motion during Indoor Walking and Cycling

This study investigated the factors that influence core muscle endurance, i.e., the symmetry of frontal core motion during indoor walking and cycling, the symmetry of lateral core muscle endurance, the symmetry of the hip abductor strength, the weekly workout time and fast walking and cycling speeds, while controlling for gender. Seventy-nine healthy young adults participated in this study. In a regression analysis, the core muscle endurance time was the dependent variable. The independent variables were the symmetry of frontal core motion (measured using a wireless earbud sensor during walking and cycling), the symmetry of side plank time and of hip abductor strength, the weekly workout time and fast walking and cycling speeds. In the multiple regression analysis, weekly workout time, fast walking speed, symmetry of frontal core motion during fast cycling and symmetry of lateral side plank time predicted core muscle endurance (adjusted R2 = 0.42). Thus, clinicians and fitness personnel should consider the association of core muscle endurance with the symmetry of frontal core motion during cycling and the symmetry of side plank holding time, as well as with the weekly workout time and a fast walking speed, when designing core muscle exercise programmes.

Review of studies on concrete columns confined by lateral reinforcement under axial compression and lateral cyclic loading

AbstractThe restraint of lateral reinforcement can effectively improve the bearing capacity and deformation capacity of confined concrete columns. Generally, the behavior of confined concrete column under axial compression and lateral cyclic loading is a complex process and has been the subject of numerous studies dating from last century. This paper presents a review to summarize and discuss the investigations of concrete columns confined by lateral reinforcements under axial compression and lateral cyclic loading with the aim of obtaining a clear understanding on the mechanism and performance of confined concrete column. In this paper, a test database of confined concrete columns under axial compression and lateral cyclic loading is established, presented, and evaluated. The detailed provisions of confined concrete columns from current codes are concluded and it is found that these codes neglect the beneficial effect of lateral reinforcement on shear bearing capacity of confined concrete columns under lateral cyclic loading. Additionally, the stress–strain models and development of lateral reinforcement strain/stress in confined concrete columns under axial compression are mainly presented and discussed. Moreover, theoretical and experimental studies on seismic behavior of confined concrete columns are evaluated, including compression‐flexure calculation, shear bearing capacity, ductility, energy dissipation capacity, and other detailed requirements. Furthermore, main influential factors of confined concrete columns under axial compression and lateral cyclic loading are discussed, respectively and it is founded that the synergy work of longitudinal and lateral reinforcement, and the deformation coordinated relationship between lateral reinforcement and core concrete significantly affect the bearing capacity and deformation capacity of confined concrete columns. Therefore, further studies are suggested to optimize and quantify the strength grade combination relationship between lateral reinforcement, longitudinal reinforcement, and concrete to achieve economical design and construction.

Clinical Efficacy of Cervical Core Strengthening Exercise in the Treatment of Cervicogenic Headache

<bold>Objective</bold> To explore the clinical efficacy of cervical core strengthening exercise in the treatment of cervicogenic headache. <bold>Methods</bold> A total of 168 patients with cervicogenic headache who visited Rehabilitation Medicine Department of Beijing Jishuitan Hospital from January 2016 to December 2017 were randomly divided into control group and treatment group using a random number table sampling method, with 84 cases in each group. The patients in the control group were treated with conventional treatment, including taking rest, treating with therapeutic modalities, oral drugs. Therapeutic modalities included ultrashort wave, interferential current therapy, laser, magnetic therapy (15 minutes per time, once per day). On the other hand, drug therapy included nonsteroidal anti-inflammatory drugs, eperisone hydrochloride and gabapentin, etc. In addition of the conventional treatment, the treatment group also participated in strengthening exercise of anterior, posterior and lateral core muscles of cervical vertebra (each movement held for 10 seconds, 20 movements at a time, and 5 sets of exercise per day) for 4 weeks. Furthermore, it was changed to 2 sets of exercise per day for 12 months. In addition, visual analog scale (VAS) score, Hamilton's Depression Scale-17 (HAMD-17), Pittsburgh Sleep Quality Index (PSQI) and Patients' Global Impression of Change (PGIC) scale were evaluated before treatment and at 1 month, 3 months and 12 months of treatment. <bold>Results</bold> In terms of the intragroup comparison, the VAS score in control group improved at 1 month of treatment compared with that before treatment (<italic>P</italic>&lt;0.05). There were no significant changes in each index at each time point (<italic>P</italic>&gt;0.05). By contrast, the VAS, HAMD-17, PSQI and PGIC scores in the treatment group improved at 1 month, 3 months and 12 months of treatment compared with those before treatment (<italic>P</italic>&lt;0.05). The comparison between groups showed that no significant differences were found in VAS, HAMD-17, PSQI and PGIC scores between the two groups at 1 month of treatment (<italic>P</italic>&gt;0.05). Apart from that, the VAS, HAMD-17, PSQI and PGIC scores in the treatment group improved more than those in the control group at 3 months and 12 months of treatment (<italic>P</italic>&lt;0.05). Specifically, at 3 months of treatment, the scores of the treatment group were VAS (2.96±1.11), HAMD-17 (25.95±5.91), PSQI (4.55±0.81), and PGIC (4.87±1.47), while the scores of the control group were VAS (5.86±1.31), HAMD-17 (36.97±7.62), PSQI (6.97±1.21), and PGIC (2.36±0.74), and the difference was statistically significant respectively (<italic>P</italic>&lt;0.05). Last, at 12 months of treatment, the treatment group's VAS (1.92±0.91), HAMD-17 (21.94±7.52), PSQI (2.32±0.61), and PGIC (5.50±1.41) were better than the control group's VAS (6.97±1.01), HAMD-17 (41.38±9.02), PSQI (5.15±1.11), and PGIC (2.50±0.91), and the difference was statistically significant respectively (<italic>P</italic>&lt;0.05). <bold>Conclusion</bold> The cervical core strengthening exercise will relieve pain, improve scores of mood and sleep in patients with cervicogenic headache.

5-kW-Level Bi-Directional High-Efficiency Pump and Signal Combiner With Negligible Beam Quality Degradation

(6+1)×1 pump and signal combiner with high power handing capability, negligible beam quality degradation and bi-directional signal transmission ability has been developed by employing signal-fiber non-taper fabrication approach and in-line active splicing process. The influences of lateral core offset and angular misalignment between the signal input and output fibers in combiner have been studied theoretically, showing that M <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> factor rather than signal efficiency is more suitable to be the evaluation criterion. Three splicing methods have been compared experimentally, revealing that the M <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> -based active splicing is the most effective to preserve beam quality and obtain good efficiency simultaneously. Signal laser transmitted backward through 25-μm fiber core has shown efficiency of 95.5% and M <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> factor deterioration no more than 10% at 1 kW of power. Combined pump from laser diodes into 400-μm fiber clad has reached beyond 5 kW of power at efficiency of 98.2%, with the maximum temperature on combiner being 70.5°C, which was tested in the condition without cooling on fiber pigtails and with flat-cleaved fiber termination aggregating thermal load. Both results indicate the effectiveness of the proposed fabrication technique to make bi-directional (6+1)×1 combiner for high power and superior beam quality fiber laser systems.

Differences in Lateral Core Muscles’ Endurance Measurementsb Adolescents with And Without Flexible Flat-Feet

Background: Flexible flatfeet are a common deformity that affects youngsters and persists throughout their lives, and it is considered to be a contributing factor in many lower limb accidents and low back discomfort. Core muscles function as trunk stabilisers, and any disruption or weakening in these muscles puts a person at risk for low back discomfort and lower limb injury. Objective: We aimed to compare the core muscles’ endurance between adolescents with and without flexible flatfeet. Patients and Methods: Thirty participants with bilateral flexible flatfeet (study group) were compared with thirty healthy participants (control group). Navicular drop test (NDT) was used to evaluate the medial longitudinal arch. Modified back extensors, modified flexion and lateral muscles’ endurance tests were used to evaluate the endurance of the core muscles. Results: There was no significant difference found in the trunk lateral muscles for left bridge (p = 0.38) and right bridge (p = 0.70) endurance time between both groups. Conclusion: There is no significant difference in the endurance of the lateral core muscles between adolescents with and without flexible flatfeet at the selected age in the early adolescent stage.

The Influence of Dentin Wall Thickness and Adhesive Surface in Post and Core Crown and Endocrown Restorations on Central and Lateral Incisors.

Post and core crowns and endocrowns perform similarly on fracture strength, but endocrowns have more repairable fractures.

Reliability of an adapted core strength endurance test battery in individuals with axial spondylarthritis

ObjectivesTo adapt the core strength endurance test battery (aCSE), previously used for testing athletes, to a target group of patients with axial spondylarthritis (axSpA), to evaluate its intra-tester reliability and its associations with disease-specific factors.MethodsA cross-sectional study was conducted at axSpA exercise therapy groups, including both axSpA patients and the physiotherapist group leaders (PTs). The aCSE was used to measure the isometric strength endurance of the ventral, lateral, and dorsal core muscle chains (measured in seconds), as well as to assess the disease-specific factors of functional status, self-reported pain, and perceived strength performance. The aCSE was repeated after 7–14 days to measure intra-tester reliability for the same rater (PT group leader). Reliability was calculated as an intra-class correlation coefficient (ICC) using a nested design. The associations between ventral, lateral, and dorsal strength endurance and the disease-specific factors were calculated using Pearson correlation coefficients.ResultsStudy participants were 13 PT group leaders and 62 axSpA patients. The latter were all capable of performing the aCSE, with the exception of one individual. A moderate to substantial intra-rater reliability (ICCs (95%CI)) was found for the ventral (0.54 (0.35, 0.74)), lateral (0.52 (0.33, 0.70)), and dorsal (0.71 (0.58, 0.86)) core muscle chains. None of the aCSE measures correlated with the disease-specific factors.ConclusionThe aCSE was found to be a reliable test battery for assessing core strength endurance in axSpA patients. Interestingly, aCSE performance was not associated with any disease-specific factors.Key Points • The adapted core strength endurance test battery measures the isometric strength of the ventral, lateral and dorsal core muscle chains. • The adapted core strength endurance test battery showed a moderate to substantial intra-rater reliability for all three muscle chains tested in axSpA patients. • No correlations were found between the adapted core strength endurance test battery and the disease-specific factors of self-reported pain, functional status and perceived strength performance.

Can we improve the detection rate of prostate cancer using standard 12-core TRUS-guided prostate biopsy? Focused on the location of prostate biopsy.

BackgroundWe assessed the effect of biopsy location on the prostate cancer detection and clinically significant prostate cancer.MethodsA total of 2774 patients with 12‐core prostate transrectal ultrasound‐guided prostate biopsy were included for per core analysis. Multivariate Cox regression analysis was performed to evaluate the effect of the location of biopsy on the prostate cancer and clinically significant prostate cancer detection.ResultsProstate cancer was found in 775 patients (27.9%) and 576 prostate cancer patients (20.8%) were found to be clinically significant. The core length (P = .043), tumor length (P < .001), and % tumor length (P < .001) were significantly different according to the biopsy location. The detection rates for prostate cancer and clinically significant prostate cancer differed significantly according to the location of biopsy. Multivariate analysis revealed that the apical core was significantly related with increased detection of prostate cancer and clinically significant prostate cancer. The lateral core, in addition to apical core, was found to be significantly related with increased detection rates of prostate cancer and clinically significant prostate cancer in men with prostate‐specific antigen <10 ng/mL.ConclusionsMore in‐depth discussions on the location of standard 12‐core prostate biopsy are considered necessary. Apical core and lateral core biopsies may be helpful, especially in patients with prostate‐specific antigen ˂10 ng/mL if additional biopsies are planned following findings of no target lesions on imaging studies.

Investigation of a Side-Polished Fiber MZI and Its Sensing Performance

A novel all-fiber Mach–Zehnder interferometer (MZI), which consists of lateral core fusion splicing of a short section of side-polished single mode fiber (SMF) between two SMFs was proposed and demonstrated. A simple fiber side-polished platform was built to control the side polished depth through a microscope. The sensitivity of the fiber MZI structure to the surrounding refractive index (RI) can be greatly improved with the increase of the side-polished depth, but has no effect on the temperature sensitivity. The sensor with a polished depth of $44.2~\mu \text{m}$ measured RI sensitivity up to −118.0 nm /RIU (RI unit) in the RI range from 1.333 to 1.387, which agrees well with simulation results by using the beam propagation method (BPM). In addition, the fiber MZI structure also can achieve simultaneous measurement of both RI and temperature. These results show its potential for use in-line fiber type sensing application.

Evaluation of different root canal filling techniques in severely curved canals by micro-computed tomography

AimTo fill the severely curved root canals with different filling techniques and to compare these techniques using micro-computed tomography (micro-CT). Materials and methodsSixty extracted mandibular first molars (degree of root canal curvature >25°) were selected. All samples were divided into four groups and filled with one of the following techniques: lateral condensation, single-cone, continuous-wave obturation, and core carrier. After they were scanned by micro-CT, the total area, filled area and void area of the root canal were calculated. The Mann–Whitney U and Kruskal–Wallis tests were used for statistical analysis (p < 0.05). ResultsIt was shown that significantly more filling material was used in the lateral condensation and core carrier technique groups at 2 and 5 mm than in the single-cone and continuous-wave obturation technique groups (p < 0.05). It was observed no statistically significant difference at 8 mm (p > 0.05). ConclusionNo technique could completely fill in root canal. Regarding the coronal part, all techniques can be used for more effective filling as long as a good condensation is achieved. The use of a plugger with an optimal size according to the localisation of root canal curvature and the choice of a heat-resistant root canal sealer affects the success of the treatment in the thermoplastic techniques.

Variability in nicotine conditioned place preference and stress-induced reinstatement in mice: Effects of sex, initial chamber preference, and guanfacine.

Relapse to smoking occurs at higher rates in women compared with men, especially when triggered by stress. Studies suggest that sex-specific interactions between nicotine reward and stress contribute to these sex differences. Accordingly, novel treatment options targeting stress pathways, such as guanfacine, an α2-adrenergic receptor agonist, may provide sex-sensitive therapeutic effects. Preclinical studies are critical for elucidating neurobiological mechanisms of stress-induced relapse and potential therapies, but rodent models of nicotine addiction are often hindered by large behavioral variability. In this study, we used nicotine conditioned place preference to investigate stress-induced reinstatement of nicotine preference in male and female mice, and the effects of guanfacine on this behavior. Our results showed that overall, nicotine induced significant place preference acquisition and swim stress-induced reinstatement in both male and female mice, but with different nicotine dose-response patterns. In addition, we explored the variability in nicotine-dependent behaviors with median split analyses and found that initial chamber preference in each sex differentially accounted for variability in stress-induced reinstatement. In groups that showed significant stress-induced reinstatement, pretreatment with guanfacine attenuated this behavior. Finally, we evaluated neuronal activation by Arc immunoreactivity in the infralimbic cortex, prelimbic cortex, anterior insula, basolateral amygdala, lateral central amygdala and nucleus accumbens core and shell. Guanfacine induced sex-dependent changes in Arc immunoreactivity in the infralimbic cortex and anterior insula. This study demonstrates sex-dependent relationships between initial chamber preference and stress-induced reinstatement of nicotine conditioned place preference, and the effects of guanfacine on both behavior and neurobiological mechanisms.

Evaluation of electromagnetic and nuclear scattering models in GATE/Geant4 for proton therapy.

PurposeThe dose core of a proton pencil beam (PB) is enveloped by a low dose area reaching several centimeters off the central axis and containing a considerable amount of the dose. Adequate modeling of the different components of the PB profile is, therefore, required for accurate dose calculation. In this study, we experimentally validated one electromagnetic and two nuclear scattering models in GATE/Geant4 for dose calculation of proton beams in the therapeutic energy window (62–252 MeV) with and without range shifter (RaShi).MethodsThe multiple Coulomb scattering (MCS) model was validated by lateral dose core profiles measured for five energies at up to four depths from beam plateau to Bragg peak region. Nuclear halo profiles of single PBs were evaluated for three (62.4, 148.2, and 252.7 MeV) and two (97.4 and 124.7 MeV) energies, without and with RaShi, respectively. The influence of the dose core and nuclear halo on field sizes varying from 2–20 cm was evaluated by means of output factors (OFs), namely frame factors (FFs) and field size factors (FSFs), to quantify the relative increase of dose when increasing the field size.ResultsThe relative increase in the dose core width in the simulations deviated negligibly from measurements for depths until 80% of the beam range, but was overestimated by up to 0.2 mm in σ toward the end of range for all energies. The dose halo region of the lateral dose profile agreed well with measurements in the open beam configuration, but was notably overestimated in the deepest measurement plane of the highest energy or when the beam passed through the RaShi. The root‐mean‐square deviations (RMSDs) between the simulated and the measured FSFs were less than 1% at all depths, but were higher in the second half of the beam range as compared to the first half or when traversing the RaShi. The deviations in one of the two tested hadron physics lists originated mostly in elastic scattering. The RMSDs could be reduced by approximately a factor of two by exchanging the default elastic scattering cross sections for protons.ConclusionsGATE/Geant4 agreed satisfyingly with most measured quantities. MCS was systematically overestimated toward the end of the beam range. Contributions from nuclear scattering were overestimated when the beam traversed the RaShi or at the depths close to the end of the beam range without RaShi. Both, field size effects and calculation uncertainties, increased when the beam traversed the RaShi. Measured field size effects were almost negligible for beams up to medium energy and were highest for the highest energy beam without RaShi, but vice versa when traversing the RaShi.

Experimental Studies on the Effect of Properties and Micro-Structure on the Creep of Concrete-Filled Steel Tubes.

To study different lateral restraints, different constituents of expansion agents, the influence of different steel ratios, and concrete creep properties, we carried out experiments with lateral restraint and without lateral restraint conditions separately on 12 specimens with the expansion agent content accounting for 4%, 8%, and 12% respectively. In addition, the creep tests were performed on specimens with different steel ratios of 0.0%, 3.8%, 6.6%, and 9.2%. The test results show that the lateral restraint improves the strength of the system (concrete-filled steel tubes) which resists further load after the concrete ultimate strength is surpassed and reduces the creep. The creep degree of the concrete-filled steel tube with lateral restraint is about 0.09–0.30 times smaller than that of the tube without lateral restraints. The creep degree of the concrete-filled steel tube increases as the steel ratio decreases. Creep tests with different amounts of expansion agent indicate that the creep degree of the concrete structure increases as expansion agent content decreases. To study the internal mechanism of the creep of concrete-filled steel tubes with different lateral restraints and different expansion agent concentrations, a microscopic pore structure test on the steel core concrete was conducted using the RapidAir457 pore structure instrument. Microscopic studies show that the air content and the length of the bubble chord of the laterally restrained core concrete are lower than those without lateral restraint core concrete. The amount of air content and the length of the bubble chord of core concrete specimens increase as the expansion agent content in the core concrete specimens decreases from 12% to 4%. Under the same external loading conditions, as steel ratio increases, the lateral restraint causes a further reduction of creep. The results of this study suggest that the creep of concrete can be reduced by selecting appropriate lateral restraint conditions and an optimal amount of expansion agent in the mix design of concrete for concrete-filled steel tubes.

Research on the Thrust Characteristics and Temperature Rise of Slot-less Tubular Linear Motor for Active Vehicle Suspension

This paper presents a Slot-less Tubular Permanent Magnet Linear Motor (ST-PMLM), which does not have the cogging structure in the stator. Meanwhile, its lateral stator core doesn’t split, so the motor only has longitudinal edge effect. Since the ST-PMLM is supposed to be used as the active damper for vehicle suspension system, this paper focus on two aspects: increasing the output thrust and restraining the thrust fluctuation of the motor. Firstly, the equivalent magnetic circuit model of the ST-PMLM is established. The influences of structural parameters, including the thickness of the magnetic pole, the length of the air gap, the thickness of primary iron core and the thickness of primary winding, on the air gap flux density and the output thrust are analyzed. Then, the distribution of the magnetic field at the end of the primary iron core is observed. Length compensation in the end of primary iron core is adopted in order to reduce the thrust fluctuation. Finally, the prototype of ST-PMLM is developed and the experiment test bench is built. Based on the no-load test of the prototype, the effectiveness of the primary core length compensation in suppressing end effects and inhibiting fluctuations are verified.

Material Stiffness and Cutting Parameters for Honeycomb Aluminum Sandwich Panel: a Comparison with Bulk Material

Abstract Aluminum sandwich panel provides a high-strength, light-weight structural material for use in aircraft and aerospace applications such as cabin bulkheads, rotor blades, and luggage and cargo unit load devices. This unique material also has application in many other industries such as machine tool enclosures, museum exhibits, marine craft bulkheads, and hurricane panels for storm survivability. This material, consisting of aluminum face sheets surrounding an aluminum honeycomb core, offers very high rigidity in a low density material. Machining this material is quite challenging due to variable cutting conditions in the low density, low lateral stiffness honeycomb core. Machining often requires a significant amount of post-processing in the form of manual removal of the partially released core walls (flags) along machined edges. The purpose of this work is to reduce the flagging created in the machining of this material. The first step to improving the cutting conditions is to better understand the causes that impact them. In this pursuit, a series of experiments was conducted to measure, quantify, and study the cutting forces during the machining of aluminum sandwich panel. A force dynamometer was used to measure forces during slot milling in bulk aluminum generating cutting coefficients for the force model. Cutting results in bulk aluminum showed generally good agreement with the model with over-predictions ranging from 5 to 20% depending on the feed rate. A series of cutting tests was then conducted on the aluminum sandwich panel in order to decouple the machining forces for the face sheets, the honeycomb core, and combinations of face sheets and core. The data revealed vibration in the honeycomb material that were significantly worse for shallower depths of cut involving the top face sheet and the upper portion of the honeycomb structure despite efforts at stiffening the fixture. The data showed force spikes that correlate with specific engagement conditions in the honeycomb structure. Peak forces were measured as high as 400N though it is not entirely clear whether these peak values are representative of actual peak forces or a combination of peak force with harmonic vibration. The resulting cut walls showed signs of tearing, rubbing, and remaining cell walls indicating that for much of the cut, ideal shearing of the material did not occur. The research highlights the need for further study of the actual mechanism of cell wall removal in this complex cutting environment.

Effects of core stability training on throwing velocity and core strength in female handball players

This study investigated the effect of a six-week in-season core stability training (CST) intervention on maximal throwing velocity and core strength parameters. Twenty female handball players (23.4±4.4 years, 168.4±3.5 cm, and 66.9±9.2 kg) were randomized into a CST intervention group (N.=10) and a control group (CON, N.=10). Throwing velocity, maximal isometric strength (MIS) and endurance strength of the ventral, dorsal and lateral core muscle chains were measured before and after progressive, six-week core stability training in the CST group. Core endurance of both lateral core muscle chains (LR: F=7.03, P=0.017; LL: F=6.31, P=0.022;) and MIS of the left lateral core muscle chain (LL: F=7.08, P=0.019) was significantly improved in CST compared to CON group after 6 weeks. Additionally, CST group significantly increased MIS of the lateral right core muscles (21%, P=0.042) and the ventral core endurance (35%, P=0.016) compared to baseline. Although both groups significantly increased throwing velocity of the jump throw after the intervention (CST 12%, P=0.001; CON 8%, P=0.009), throwing velocity of the standing throw remained unchanged. A six-week CST intervention effectively increased the isometric strength and endurance of selected core muscles but did not significantly enhance throwing velocity compared to standard training.