Laser system generating 250-mJ bunches of 5-GHz repetition rate, 12-ps pulses.

We report on a high-energy solid-state laser based on a master-oscillator power-amplifier system seeded by a 5-GHz repetition-rate mode-locked oscillator, aimed at the excitation of the dynamic Casimir effect by optically modulating a microwave resonator. Solid-state amplifiers provide up to 250 mJ at 1064 nm in a 500-ns (macro-)pulse envelope containing 12-ps (micro-)pulses, with a macro/micropulse format and energy resembling that of near-infrared free-electron lasers. Efficient second-harmonic conversion allowed synchronous pumping of an optical parametric oscillator, obtaining up to 40 mJ in the range 750-850 nm

Colorectal Cancer Stage at Diagnosis Before vs During the COVID-19 Pandemic in Italy

IMPORTANCE Delays in screening programs and the reluctance of patients to seek medical attention because of the outbreak of SARS-CoV-2 could be associated with the risk of more advanced colorectal cancers at diagnosis. OBJECTIVE To evaluate whether the SARS-CoV-2 pandemic was associated with more advanced oncologic stage and change in clinical presentation for patients with colorectal cancer. DESIGN, SETTING, AND PARTICIPANTS This retrospective, multicenter cohort study included all 17 938 adult patients who underwent surgery for colorectal cancer from March 1, 2020, to December 31, 2021 (pandemic period), and from January 1, 2018, to February 29, 2020 (prepandemic period), in 81 participating centers in Italy, including tertiary centers and community hospitals. Follow-up was 30 days from surgery. EXPOSURES Any type of surgical procedure for colorectal cancer, including explorative surgery, palliative procedures, and atypical or segmental resections. MAIN OUTCOMES AND MEASURES The primary outcome was advanced stage of colorectal cancer at diagnosis. Secondary outcomes were distant metastasis, T4 stage, aggressive biology (defined as cancer with at least 1 of the following characteristics: signet ring cells, mucinous tumor, budding, lymphovascular invasion, perineural invasion, and lymphangitis), stenotic lesion, emergency surgery, and palliative surgery. The independent association between the pandemic period and the outcomes was assessed using multivariate random-effects logistic regression, with hospital as the cluster variable. RESULTS A total of 17 938 patients (10 007 men [55.8%]; mean [SD] age, 70.6 [12.2] years) underwent surgery for colorectal cancer: 7796 (43.5%) during the pandemic period and 10 142 (56.5%) during the prepandemic period. Logistic regression indicated that the pandemic period was significantly associated with an increased rate of advanced-stage colorectal cancer (odds ratio [OR], 1.07; 95%CI, 1.01-1.13; P = .03), aggressive biology (OR, 1.32; 95%CI, 1.15-1.53; P < .001), and stenotic lesions (OR, 1.15; 95%CI, 1.01-1.31; P = .03). CONCLUSIONS AND RELEVANCE This cohort study suggests a significant association between the SARS-CoV-2 pandemic and the risk of a more advanced oncologic stage at diagnosis among patients undergoing surgery for colorectal cancer and might indicate a potential reduction of survival for these patients

High peak-power diode-pumped passively Q-switched Nd:YVO4 laser

We report on a passively Q-switched diode-pumped Nd:YVO4 laser polarized along the a axis (corresponding to the smallest value of emission cross section at 1064 nm), generating 157-μJ pulses with 6.0-ns time duration (> 20 kW peak power) and 3.6 W of average power at 1064 nm with good beam quality ( M2 < 1.4). The selection of the polarization was performed by a novel technique relying on the birefringence of the laser crystal and on the misalignment sensitivity of the resonator

1.5 Watt passively Q-switched diode-pumped cw Nd:YAG laser

A medium-power all-solid-state diode-pumped cw Nd:YAG laser, passively Q-switched employing Cr4+:YAG as saturable absorber, has been developed. Optimum coupling operation at the 1064 nm working wavelength resulted in 100 uJ, 36 ns, nearly diffraction limited pulses at 15 kHz repetition frequency, with 1.5 W average power output. We discuss the characterisation of the passive Q-switching elements and the laser operation

Method for selecting the polarization of the laser beam oscillating inside a laser cavity

Method for selecting the polarization of the laser beam inside a laser cavity, which provides generation of a laser beam (1) inside said resonant laser cavity (20), comprising optical media (8,10,9; 9',12; 9',14; 13; 33), which include one or more birefringent optical media (9; 12; 14; 13). According to the invention, said birefringent optical media (9; 12; 14; 13) are used for inducing a double refraction effect on the laser beam (1) and separating the propagation directions of the different polarization components (2,3) of the laser beam (1) at the interface (22; 32; 41,42; 51,52; 61,62) between said media (9; 12; 14; 13) and a second medium with a different refractive index, providing a plurality of separate resonance directions (6,7) which are distinct for the different polarization components (2, 3), and selectively align the cavity optical axis (20) on one of said resonance positions (6,7) through the adjustment of the position of one or more optical elements (8,9,10; 9',12; 9',14; 13,33) forming said cavity (20)

2.4-W intracavity doubled cw Nd:GdVO4 laser at 670 nm

Intracavity second harmonic generation with diode-pumped Nd:GdVO4 laser and LBO nonlinear crystal yielded as much as 2.4 W in a TEM00 mode at 671 nm, with a very compact resonator. The laser is highly efficient and low-noise

High-brightness 2.4-W continuous-wave Nd:GdVO4 laser at 670 nm

We report on a diode-pumped 1.3-mm Nd:GdVO4 cw laser, intracavity doubled for highly efficient generation of red light. We obtained as much as 2.4 W of power at 670 nm (corresponding to 26% optical-to-optical efficiency) in a nearly TEM00 mode and with small amplitude noise. To the best of our knowledge, these results represent the highest performance at this wavelength for cw solid-state lasers

The prognostic role of metastatic lymph node ratio in colon cancer: a retrospective cohort study on 241 patients in a single center

The detection of nodal status is based on examination of lymph nodes (LN) after the tumor surgical resection and the current guidelines recommend to examine atleast 12 regional LN. An inadequate number of examined LN may lead to a lower N stage or to a false-negative nodal disease. To overcome these issues, many authors proposed to consider the metastatic lymph node ratio (mLNR). MLNR is the ratio of the number of metastatic LN to the number of examined LN