Bright circularly polarized soft X-ray high harmonics for X-ray magnetic circular dichroism

We demonstrate, to our knowledge, the first bright circularly polarized high-harmonic beams in the soft X-ray region of the electromagnetic spectrum, and use them to implement X-ray magnetic circular dichroism measurements in a tabletop-scale setup. Using counterrotating circularly polarized laser fields at 1.3 and 0.79 µm, we generate circularly polarized harmonics with photon energies exceeding 160 eV. The harmonic spectra emerge as a sequence of closely spaced pairs of left and right circularly polarized peaks, with energies determined by conservation of energy and spin angular momentum. We explain the single-atom and macroscopic physics by identifying the dominant electron quantum trajectories and optimal phase-matching conditions. The first advanced phase-matched propagation simulations for circularly polarized harmonics reveal the influence of the finite phase-matching temporal window on the spectrum, as well as the unique polarization-shaped attosecond pulse train. Finally, we use, to our knowledge, the first tabletop X-ray magnetic circular dichroism measurements at the N_4,5 absorption edges of Gd to validate the high degree of circularity, brightness, and stability of this light source. These results demonstrate the feasibility of manipulating the polarization, spectrum, and temporal shape of high harmonics in the soft X-ray region by manipulating the driving laser waveform.High-harmonic generation (HHG) results from an extreme nonlinear quantum response of atoms to intense laser fields. When implemented in a phase-matched geometry, bright, coherent HHG beams can extend to photon energies beyond 1.6 keV (1, 2). For many years, however, bright HHG was limited to linear polarization, precluding many applications in probing and characterizing magnetic materials and nanostructures, as well as chiral phenomena in general. Although X-ray optics can in principle be used to convert extreme UV (EUV) and X-ray light from linear to circular polarization, in practice such optics are challenging to fabricate and have poor throughput and limited bandwidth (3). A more appealing option is the direct generation of elliptically polarized (4–6) and circularly polarized (7–9) high harmonics. In recent work we showed that by using a combination of 0.8 and 0.4 µm counterrotating driving fields, bright (i.e., phase-matched) EUV HHG with circular polarization can be generated at wavelengths λ > 18 nm and used for EUV magnetic dichroism measurements (10–13).Here we make, to our knowledge, the first experimental demonstration of circularly polarized harmonics in the soft X-ray region to wavelengths λ < 8 nm, and use them to implement soft X-ray magnetic circular dichroism (XMCD) measurements using a tabletop-scale setup. By using counterrotating driving lasers at 0.79 µm (1.57 eV) and 1.3 µm (0.95 eV), we generate bright circularly polarized soft X-ray HHG beams with photon energies greater than 160 eV (14) and with flux comparable to the HHG flux obtained using linearly polarized 800-nm driving lasers (15). Moreover we implement, to our knowledge, the first advanced simulations of the coherent buildup of circularly polarized high harmonics to show how the macroscopic phase-matching physics and ellipticity of the driving lasers influence the HHG spectra, number of bright attosecond bursts, and the degree of circular polarization.This work presents several new capabilities and findings. First, circularly polarized HHG provides a unique route for generating bright narrowband (λ/Δλ > 400) harmonic peaks in the soft X-ray region, to complement the soft X-ray supercontinua that are produced with linearly polarized mid-IR lasers (2, 15, 16). This capability is significant because it provides an elegant and efficient route for shaping soft X-ray light by manipulating the driving laser light, and is very useful for applications in high-resolution coherent imaging (17–21) and photoelectron spectroscopies. Second, we show that the macroscopic phase-matching physics of circularly polarized soft X-ray HHG driven by mid-IR lasers has similarities to linearly polarized HHG, where the number of bright attosecond bursts is limited by the finite phase-matching temporal window. Third, we implement the first tabletop XMCD measurements at the N_4,5 absorption edges of Gd. The Gd/Fe multilayer sample is a candidate material for next-generation all-optical magnetic storage devices (22), but has been inaccessible to HHG XMCD until now. This capability also opens up the possibility of probing spin dynamics in rare-earth elements using HHG, which has been successfully used for 3d transition metals to uncover the fastest spin dynamics using EUV HHG (23, 24). Finally, and most importantly, these results demonstrate the universal nature of circularly polarized HHG that can be generated across the EUV and soft X-ray spectral regions using a broad range of driving laser wavelengths.     

Phenalenyl based neutral radical as a novel electrochromic material modulating visible to short-wave infrared light

Applications for energy saving smart windows require materials which can switch from transmissive to black states in both the visible and short-wave IR range. We introduce an electrochromic phenalenyl based neutral radical small molecule and design devices capable of modulating light in both of these ranges.

A phenalenyl based small molecule can modulate from a transmissive to black state in the visible to short-wave infrared range.     

Dipyridamole-Atropine-Induced Myocardial Infarction in a Patient with Patent Epicardial Coronary Arteries

BACKGROUND: The diagnostic accuracy of the physical and pharmacological stress echocardiography tests is higher than routine exercise electrocardiography. They have an acceptable safety profile and have been rarely associated with severe adverse effects. CASE REPORT: We present a case of acute anterior myocardial reinfarction immediately after exercise and pharmacological (dipyridamole-atropine) stress echocardiography testing 1 month after successful stent implantation in LAD. Our patient was a 43-year-old man with a history of heavy smoking and hypertension. Remarkably, the stress echocardiogram was non-diagnostic few hours before the infarction occurred. Angiography performed 4 months after the reinfarction revealed neither a culprit lesion nor stent thrombosis. CONCLUSION: Aggressive "last generation" pharmacological stress testing may provide optimal diagnostic accuracy, but as in our case, complications may occur, even after negative stress testing. To our knowledge, this is the first reported case of an acute myocardial infarction as a severe complication of stress testing, which developed in a patient after stent implantation.     

Mining injuries in Serbian underground coal mines - A 10-year study

Mining, especially underground coal mining, has always been a dangerous occupation. Injuries, unfortunately, even those resulting in death, are one of the major occupational risks that all miners live with. Despite the fact that all workers are aware of the risk, efforts must be and are being made to increase the safety of mines. Injury monitoring and data analysis can provide us with valuable data on the causes of accidents and enable us to establish a correlation between the conditions in the work environment and the number of injuries, which can further lead to proper preventive measures. This article presents the data on the injuries in Serbian coal mines during a 10-year period (2000-2009). The presented results are only part of an ongoing study whose aim is to assess the safety conditions in Serbian coal mines and classify them according to that assessment.     

Predictive factors of recurrence after pediatric acute pericarditis

ObjectiveThe predisposing factors for pericarditis recurrence in the pediatric population have not yet been established. This study aimed to define the risk factors for the unfavorable prognosis of pediatric acute pericarditis.MethodsThis was a retrospective study that included all patients with acute pericarditis treated from 2011 to 2019 at a tertiary referent pediatric center.ResultsThe study included 72 children. Recurrence was observed in 22.2% patients. Independent risk factors for recurrence were: erythrocyte sedimentation rate ≥ 50 mm/h (p = 0.003, OR 186.3), absence of myocarditis (p = 0.05, OR 15.2), C-reactive protein ≥ 125 mg/L (p = 0.04, OR 1.5), and non-idiopathic etiology pericarditis (p = 0.003, OR 1.3). Corticosteroid treatment in acute pericarditis was associated with a higher recurrence rate than treatment with non-steroid anti-inflammatory therapy (p = 0.04). Furthermore, patients treated with colchicine in the primary recurrence had lower recurrence rate and median number of repeated infections than those treated without colchicine (p = 0.04; p = 0.007, respectively).ConclusionIndependent risk factors for recurrence are absence of myocarditis, non-idiopathic etiology pericarditis, C-reactive protein ≥ 125 mg/L, and erythrocyte sedimentation rate ≥ 50 mm/h. Acute pericarditis should be treated with non-steroid anti-inflammatory therapy. A combination of colchicine and non-steroid anti-inflammatory drugs could be recommended as the treatment of choice in recurrent pericarditis.     

Mycosis fungoides and Sézary syndrome: Australian clinical practice statement

Primary cutaneous lymphomas represent a heterogeneous group of T‐ and B‐cell lymphomas with distinct clinical presentations, histopathologic features, treatment approaches and outcomes. The cutaneous T‐cell lymphomas, which include mycosis fungoides and Sézary syndrome, account for the majority of the cutaneous lymphomas. This Clinical Practice Statement is reflective of the current clinical practice in Australia. An expanded form of the Clinical Practice Statement (and updates), along with helpful patient resources and access to support groups, can be found at the following ( http://www.australasianlymphomaalliance.org.au ).