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Background: The purpose of this long-term (up to 17 years) follow-up study was to determine: (1) clinical results and evidence of clicking or squeaking sounds; (2) radiographic results, including rates of osseointegration, bone remodeling, and osteolysis; (3) rates of complications including thigh pain, periprosthetic fracture, and ceramic fracture; (4) rates of revision; and (5) survival rates of implants in patients younger than 30 years.Methods: We analyzed the results of 240 consecutive primary total hip arthroplasty in 180 patients (118 men and 62 women who had a mean age of 27 years (range, 21 to 30 years)). The mean follow-up was 16 years (range, 14 to 17 years).Results: Mean Harris hip score, Western Ontario and McMaster Universities score, and University of California, Los Angeles activity score were 93 points, 18 points, and 7 points, respectively, at final follow-up. Radiographically, all of the acetabular components and all but two femoral components were well-fixed at the final follow-up. No hip had osteolysis or exhibited Grade 3 stress shielding. All but two patients had no groin or thigh pain. No hip had a periprosthetic or ceramic fracture. Eight hips (3%) exhibited squeaking sounds. Two acetabular components and two femoral stems were revised. The survival of the acetabular and femoral component was 99.2% (95% confidence interval, 94 to 100%).Conclusion: The results of the present long-term study of ultra-short anatomic cementless femoral stems suggest excellent clinical and radiographic results in patients younger than 30 years. [ABSTRACT FROM AUTHOR]

Background: The purpose of this study is to determine the clinical and radiographic outcomes, mortality rate, complication rate, and revision rate of this ultra-short non-anatomic cementless femoral stem in elderly patients with a femoral neck fracture.Methods: We reviewed the results of 284 total hip arthroplasties performed with an ultra-short non-anatomic cementless stem in 280 previously active patients with a mean age of 72.8 ± 13 years (range 49-83). The mean follow-up was 9.3 years (range 7-13).Results: The mean Harris Hip Score was 86 ± 14 points at final follow-up. The mean Western Ontario and McMaster Universities Osteoarthritis Index score was 24 ± 6 points at the final follow-up. The mean University of California, Los Angeles activity score was 6 points at final follow-up. Osseointegration was seen in all acetabular (100%) and in 276 femoral components (97%). Kaplan-Meier survivorship analysis revealed that the survival rate of the femoral component at 8.3 years was 97% (95% confidence interval 91-100) and that of the acetabular component was 100% (95% confidence interval 94-100) with aseptic loosening or revision as the end point.Conclusion: An ultra-short non-anatomic cementless femoral stem in patients with good bone quality (Dorr A and some Dorr type B bone) is a safe treatment for femoral neck fracture. In patients with poor bone quality (Dorr C type), the results were very poor, and use of this stem should be avoided. [ABSTRACT FROM AUTHOR]

Ultra-short pulse lasers have already proven to be an excellent tool for material processing due to confined laser-matter interaction leading to high quality, precision and thermal-damage-free surface structuring. For the technology to be a cost-efficient and suitable for the industry, continuous research on the ways how to improve the throughput, in terms of energy and time efficiencies must be done. In this work, the ultra-short pulse lasers were used to investigate the ablation efficiency of a copper target. Laser ablation efficiency was investigated by pulse energy and beam size optimisation method for various processing parameters. Also, the efficiency of material removal by bursts of ultra-short pulses was investigated. Furthermore, it was shown that high ablation efficiency led to superior ablation quality in terms of surface roughness, which both are the most critical characteristics for industry-orientated applications. [ABSTRACT FROM AUTHOR]

Background: Long-term result of the ultra-short anatomic cementless stem in the patients with idiopathic or ethanol-induced osteonecrosis of the femoral head has not been assessed. The aim of this study is to evaluate the long-term clinical, radiographic, computed tomography scan, and dual-energy X-ray absorptiometry scanning results, and survivorship of this specific femoral stem in patients with idiopathic or ethanol-induced femoral head osteonecrosis.Methods: Two hundred fifty-six patients (335 hips) with an average age of 49.8 years (range 20-63) were enrolled in the current study. All patients underwent dual-energy X-ray absorptiometry scanning of the acetabulum and proximal femur preoperatively and at final follow-up. Computed tomography scan was obtained in all patients at final follow-up. The mean follow-up was 14.7 years (range 13-16).Results: At final follow-up, the average Harris hip score, Western Ontario and McMaster Universities Osteoarthritis Index score, and University of California, Los Angeles activity score were 94 points, 12 points, and 8 points, respectively. Four stems (1%) underwent revision for aseptic loosening. One acetabular component (0.3%) was revised for recurrent dislocation. No hip was revised for squeaking or clicking sound. Survivorship of the femoral stem was 99.0% (95% confidence interval 94-100) and that of the acetabular component was 99.4% (95% confidence interval 95-100) at 14.7 years.Conclusion: Ultra-short proximal loading anatomic uncemented femoral stems with ceramic-on-ceramic bearings have excellent survivorship free from aseptic loosening and good clinical results at long term.Level Of Evidence: Level IV. [ABSTRACT FROM AUTHOR]

In this paper we describe a new method for the realization of two-color femtosecond radiation pulses in a seeded free-electron laser (FEL). The two-color pulses are obtained from two electron bunches and a chirped seeding laser. Compared to the previous methods based on seeded FELs, our method has the advantages of producing two-color FEL pulses with more flexible tunability both in the pulse durations and separations. Numerical simulations for the Dalian Coherent Light Source confirm that femtosecond XUV pulses with variable pulse durations and time delay can be directly generated from a chirped seed laser at 250 nm by using this technique. We also show the possibility of performing a proof-of-principle experiment of this technique based on the Shanghai Deep-Ultraviolet FEL facility. [ABSTRACT FROM AUTHOR]

• Elite HRV and Welltory are valid and reliable smartphone applications and can be used to monitor HRV in elite endurance athletes. • Monitoring of the stress and recovery process is crucial in the population of elite endurance athletes. • The HRV use implemented in friendly technology like smartphone applications can substantially increase the compliance of this population. Heart rate variability (HRV) has been proposed as a useful marker that can show the performance adaptation and optimize the training process in elite athletes. The development of wearable technology permits the measurement of this marker through smartphone applications. The purpose of this study is to assess the validity and reliability of short and ultra-short HRV measurements in elite cyclists using different smartphone applications. Twenty-six professional cyclists were measured at rest in supine and in seated positions through the simultaneous use of an electrocardiogram and two different smartphone applications that implement different technologies to measure HRV: Elite HRV (with a chest strap) and Welltory (photoplethysmography). Level of significance was set at p < 0.05. Compared to an electrocardiogram, Elite HRV and Welltory showed no differences neither in supine nor in seated positions (p > 0.05) and they showed very strong to almost perfect correlation levels (r = 0.77 to 0.94). Furthermore, no differences were found between short (5 min) and ultra-short (1 min) length measurements. Intraclass correlation coefficient showed good to excellent reliability and the standard error of measurement remained lower than 6%. Both smartphone applications can be implemented to monitor HRV using short- and ultra-short length measurements in elite endurance athletes. [ABSTRACT FROM AUTHOR]

Abstract: In this paper, a proposal to generate intense ultra-short free-electron laser (FEL) pulses at Shanghai deep ultraviolet FEL (SDUV-FEL) by combining the chirped pulse amplification (CPA) technique with the high-gain harmonic generation (HGHG) technique is presented. In this proposal, a frequency chirped seed pulse obtained by stretching an ultra-short laser pulse is first used to create frequency-chirped bunching at the laser harmonics in an electron beam; then the frequency chirped harmonic radiation is amplified by an energy chirped electron beam; finally the output radiation pulse which inherits the properties of the seed pulse is compressed to provide an ultra-intense ultra-short radiation pulse. The feasibility and performance of this CPA-HGHG scheme are studied with start-to-end simulations using the parameters of SDUV-FEL. The effects of frequency chirped seed pulse on different stages of FEL gain in the radiator has been studied. It is found that the beam energy chirp is not necessary to generate frequency chirped pulse in the coherent harmonic generation (CHG) regime where a short radiator with bandwidth larger than or comparable to the seed pulse is used. This makes the CPA-CHG scheme well-suited for generating intense ultra-short radiation pulse in synchrotron light sources. On the other hand, a proper energy chirp to match the frequency chirp of the seed laser is critical in CPA-HGHG scheme where a long radiator is used. Using the beam parameters at SDUV-FEL as a representative example, we show that a frequency chirped UV pulse obtained via CPA-HGHG scheme can be compressed by over one order of magnitude by an optical pulse compressor. This technique has the potential of generating ultra-intense ultra-short XUV radiation pulses directly from a commercial infrared seed laser and may open new research opportunities for strong-field physics and ultrafast sciences. [Copyright &y& Elsevier]

Our research aimed at providing methodologically strong evidence for the reliability of HRV analysis of ultra-short (10–150 s) ECGs compared to the benchmark of 300 s. Furthermore, we evaluated the retainment of HRV differences between participants with definite cardiac autonomic neuropathy (dCAN) and controls as ECG recording length was reduced to 10 s. Pre-processed ECG recordings from 11 individuals with dCAN and 76 healthy controls were used to determine SDNN, RMSSD, Low Frequency (LF) and High Frequency (HF) and assess whether the reliability of HRV features remains comparable for ultra-short ECG time series. For frequency domain analysis, the Lomb-Scargle-Periodogram (LSP) and Fast-Fourier-Transform (FFT) approaches were compared. Nonparametric areas under the curve (AUCs) were estimated to examine the overall ability of ultra-short HRV to classify dCAN from ECGs of 10–300 s. RMSSD and HF were reliable and retained significant differences between control and dCAN from ECGs down to 10 s. SDNN and LF could be considered reliable in recordings of at least 30 s. LSP and FFT yielded comparable results. Most prevalent group differences were found for LF between 60 and 300 s. RMSSD and HF were reliable HRV features showing excellent potential for the classification of dCAN from 10-s ECG strips. For recordings longer than one minute, LF proved to be reliable and yielded best discrimination results. The current research indicated that ultra-short HRV analysis has the potential to become a time-efficient and accurate diagnostic tool for dCAN in clinical practice. [ABSTRACT FROM AUTHOR]

FELiChEM is a new infrared free-electron laser (FEL) oscillator user facility in Hefei, and has achieved the first lasing at 15 μ m in June, 2019. To improve the temporal resolution for fulfilling the user demands, in this context, we propose an operation mode of generating high-power ultra-short FEL pulses by shortening the electron bunch and enhancing the FEL gain with a small cavity length detuning. The existing magnetic chicane is used to compress the electron bunch and increase its peak current. Taking the 10 μ m FEL as an example, start-to-end simulations demonstrate that the FEL power can be greatly enhanced while the pulse duration is as short as one hundred femtoseconds. An energy slit provides an additional option that can further shorten the bunch length and reduce the energy spread by cutting off the bunch head and tail. With the energy slit on, all the minor spikes inside the FEL pulse will be further suppressed and only the main spike will be preserved. [ABSTRACT FROM AUTHOR]