ABSTRACT
BACKGROUND: Sarcopenia is a syndrome marked by a gradual and widespread reduction in skeletal muscle mass and strength, as well as a decline in functional ability, which is associated with malnutrition, hormonal changes, chronic inflammation, disturbance of intestinal flora, and exercise quality. Pancreatoduodenectomy is a commonly employed clinical intervention for conditions such as pancreatic head cancer, ampulla of Vater cancer, and cholangiocarcinoma, among others, with a notably high rate of postoperative complications. Sarcopenia is frequent in patients undergoing pancreatoduodenectomy. However, data regarding the effects of sarcopenia in patients undergoing pancreaticoduodenectomy (PD) are both limited and inconsistent. AIM: To assess the influence of sarcopenia on outcomes in patients undergoing PD. METHODS: The PubMed, Cochrane Library, Web of Science, and Embase databases were screened for studies published from the time of database inception to June 2023 that described the effects of sarcopenia on the outcomes and complications of PD. Two researchers independently assessed the quality of the data extracted from the studies that met the inclusion criteria. Meta-analysis using RevMan 5.3.5 and Stata 14.0 software was conducted. Forest and funnel plots were used, respectively, to demonstrate the outcomes of the sarcopenia group vs the non-sarcopenia group after PD and to evaluate potential publication bias. RESULTS: Sixteen studies encompassing 2381 patients were included in the meta-analysis. The patients in the sarcopenia group (n = 833) had higher overall postoperative complication rates [odds ratio (OR) = 3.42, 95% confidence interval (CI): 1.95-5.99, P < 0.0001], higher Clavien-Dindo class ≥ III major complication rates (OR = 1.41, 95%CI: 1.04-1.90, P = 0.03), higher bacteremia rates (OR = 4.46, 95%CI: 1.42-13.98, P = 0.01), higher pneumonia rates (OR = 2.10, 95%CI: 1.34-3.27, P = 0.001), higher pancreatic fistula rates (OR = 1.42, 95%CI: 1.12-1.79, P = 0.003), longer hospital stays (OR = 2.86, 95%CI: 0.44-5.28, P = 0.02), higher mortality rates (OR = 3.17, 95%CI: 1.55-6.50, P = 0.002), and worse overall survival (hazard ratio = 2.81, 95%CI: 1.45-5.45, P = 0.002) than those in the non-sarcopenia group (n = 1548). However, no significant inter-group differences were observed regarding wound infections, urinary tract infections, biliary fistulas, or postoperative digestive bleeding. CONCLUSION: Sarcopenia is a common comorbidity in patients undergoing PD. Patients with preoperative sarcopenia have increased rates of complications and mortality, in addition to a poorer overall survival rate and longer hospital stays after PD.
ABSTRACT
We have proposed and demonstrated the generation of a high-energy, ultrashort pulse duration, GHz pulse burst polarization-maintaining fiber amplification system that utilizes both chirped-pulse amplification and self-similar amplification techniques. Such hybrid fiber amplification system produces 22 µJ-energy bursts of 200 pulses with a 1.02-GHz intra-burst pulse repetition rate and a 1-MHz inter-burst repetition rate. The center wavelength of the amplified compressed pulse is 1065â nm, with a 3â dB spectral bandwidth of 65â nm. The pulse duration of optimal compression is â¼35 fs, which represents the shortest pulse duration reported to date for any multi-microjoule class amplification system with a repetition rate at the GHz level. At the same time, only common double-cladding Yb3+-doped fiber is used as the gain fiber, without any large-mode-area Yb3+-doped photonic crystal fiber, makes the system compact and reliable by the simple fusion operation.
ABSTRACT
In this paper, we study the limitations of decreasing the repetition rate for the narrowband dissipative soliton picosecond (ps) pulsed Figure-9 fiber laser with periodically saturable absorber (SA), and demonstrate how to decrease the repetition rate of this kind of fiber laser. By asymmetrically increasing the passive fiber length of nonlinear amplifying loop mirror (NALM) to lower SA saturation power, Q-switching instability can be avoided, thus effectively reducing the repetition rate of ps pulses. To combat noise-like pulse caused by excessive reduction of SA saturation power, we invoke the non-reciprocal output characteristics of periodic SA, and combined with increasing the intracavity fiber length outside the SA, we further reduce the laser repetition rate. Repetition rates for â¼10 and â¼20 ps pulses are reduced to 1.7â MHz and 848 kHz, respectively, which are, to the best of our knowledge, the lowest repetition rates of Figure-9 lasers reported thus far.
ABSTRACT
The figure-9 fiber laser exhibits excellent performance, but improvement of its output pulse energy is restricted by the laser structure design that ensures self-starting mode-locking. In this paper, we propose and verify a novel method to increase the pulse energy of the self-starting figure-9 fiber laser. By reducing the linear phase shift step-by-step in a self-starting figure-9 laser and synchronously increasing the pump power, the output pulse energy can be increased while the laser can always operate in the single-pulse mode-locking region. Using a 112-MHz dispersion-managed soliton figure-9 fiber laser, the effectiveness of our proposed method is verified, and the laser output pulse energy has been successfully increased to 1.4 nJ, which is 5.6 times the pulse energy before the boost. The entire self-starting mode-locking of the laser including the program-controlled joint adjustment is less than 1s with 100% success rate of more than 100 tests. This method can in principle solve the limitation on the output pulse energy caused by the self-start of the figure-9 laser.
ABSTRACT
This paper proposes and demonstrates a method to reduce the repetition rate of all- polarization-maintaining (PM) linear-cavity picosecond dissipative soliton passively mode-locked fiber lasers. An optical coupler (OC) is inserted into the cavity to extract pulse energy, and the cavity length is increased using a low-nonlinear coefficient large-mode field fiber at the rear end of the OC, where the propagated pulse has lower energy. This enables the nonlinear phase shift to be within the tolerated value of the single pulse mode-locking even with a considerably increased cavity length; this allows reducing the laser repetition rate considerably without substantially changing the pulse characteristics. Using the proposed method, for a 0.3-nm filter bandwidth, the laser repetition rate is successfully reduced to 1.77 MHz with a nearly Fourier-transform limited pulse duration of 10 ps; it can be further reduced by optimizing the OC split ratio. The proposed method can be applied to reduce the repetition rate for a picosecond dissipative soliton passively mode-locked fiber laser with an arbitrary bandwidth filter.
ABSTRACT
The phase-locking mechanism and results of a frequency comb based on a period-doubling mode-locked (PD-ML) fiber laser were investigated. A mode-locked fiber laser was designed to switch from fundamental mode locking (FML) to PD-ML with similar output pulses by simply changing the pump. Experimental results show that the new comb teeth generated in the PD-ML are strongly correlated with the original teeth and have a consistent carrier-envelope offset (CEO) frequency. Controlling the pump and cavity length is also suited for phase-locking the PD-ML laser. With the same f-to-2f heterodyne beat system and locking circuit, phase locking of both PD-ML and FML-based optical combs with two repetition rates, and switching between them, were obtained by changing the pump only.
