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As a novel X-ray focusing technology, lobster eye micro-pore optics (MPO) feature both a wide observing field of view and true imaging capability, promising sky monitoring with significantly improved sensitivity and spatial resolution in soft X-rays. Since first proposed by Angel (1979), the optics have been extensively studied, developed and trialed over the past decades. In this Letter, we report on the first-light results from a flight experiment of the Lobster Eye Imager for Astronomy ($LEIA$), a pathfinder of the wide-field X-ray telescope of the Einstein Probe mission. The piggyback imager, launched in July 2022, has a mostly un-vignetted field of view of $18.6^\circ \times 18.6^\circ $. Its spatial resolution is in the range of 4$-$7 arcmin in FWHM and the focal spot effective area is 2$-$3 cm$^2$, both showing only mild fluctuations across the field of view. We present images of the Galactic center region, Sco X-1 and the diffuse Cygnus Loop nebular taken in snapshot observations over 0.5$-$4 keV. These are truly wide-field X-ray images of celestial bodies observed, for the first time, by a focusing imaging telescope. Initial analyses of the in-flight data show excellent agreement between the observed images and the on-ground calibration and simulations. The instrument and its characterization are briefly described, as well as the flight experiment. The results provide a solid basis for the development of the present and proposed wide-field X-ray missions using lobster eye MPO., Comment: 11 pages, 4 figures. Accepted for publication in Astrophysical Journal Letter

Pterocypsela indica L. Shih (synonym Lactuca indica L.) is an annual or biennial herbaceous plant in the Asteraceae that has a worldwide distribution. In China, it is often used as a component for traditional Chinese medicine or as a leafy edible foraged from the wild. In September 2018 in Qianxi county (27.24 N, 106.01 E) of China, where a 2-ha field of P. indica was being planted, severe powdery mildew was observed on the leaves of P. indica. Approximately 35% of leaves on a plant were symptomatic, and about 40% of the plants were infected. Colonies were circular or irregular. White patches on the adaxial surface of the leaves appeared from June to September, and necrotic symptoms were observed in the autumn. To identify the pathogen, a voucher specimen (isolate CG) was examined for morphological characters using a microscope under 40× magnification. Each unbranched conidiophore was composed of a cylindrical foot cell followed by one to three short cells, ranging in size from 90 to 270 × 8 to 14 μm (n = 40). Conidia of the pathogen were ellipsoid-ovoid to barrel-shaped and measured 25 to 34 × 17 to 22 μm (n = 40). Fibrosin bodies were absent. Fungal hyphae were septate, branched, flexuous to straight, and up to 7 μm wide. These structures were identical with those of the anamorph of Podosphaera xanthii U. Braun & N. Shishkoff (Braun and Cook 2012), previously known as Podosphaera fusca (Cho et al. 2013). The pathogen was identified as P. xanthii on the basis of morphology and the sequence of ITS1-5.8s-ITS2 region of rDNA amplified by polymerase chain reaction with universal primers ITS-1 (5′-TCCGTAGGTGAACCTGCGGaaawf-3′) and ITS-4 (5′-TCCTCCGCTTATTGATATGC-3′) (White et al. 1990). The sequence submitted on December 6, 2017 (GenBank accession MG647826.1) of the ITS region exactly matched the sequences of P. xanthii accessions (e.g., GenBank accession nos. KX369541.1 and MG754404.1). Pathogenicity of the fungus was confirmed by performing Koch’s postulate as follows. Six healthy P. indica plants at the eight-leaf stage were selected for the test in the greenhouse. They were inoculated with conidia from an infected plant. Another six plants not inoculated were regarded as controls. After the inoculation, all plants were incubated in the greenhouse for symptom development. They were kept at room temperature, >70% relative humidity, 80 Lux, and 8 h light/day. The experiments were conducted twice. Fourteen days after incubation, powdery mildew symptoms appeared on the leaves of inoculated plants, and the pathogen morphology was similar to that of the original voucher, whereas control plants were still asymptomatic. Powdery mildew caused by P. xanthii has been reported on cucurbits, composites, and solanaceous crops in China (Fan et al. 2019) and on papaya in Korea (Joa et al. 2013). However, to the best of our knowledge, this is the first report of P. xanthii causing powdery mildew on P. indica in China. Owing to abundant dissemination of conidia of P. xanthii, the disease could be a threat to P. indica in Qianxi county of China, and this geography is right for P. xanthii to possibly spread to Lactuca sativa.

Superconductivity arises from pairing of mobile electrons. The symmetry of the electron-pair wave function contains important clues about the mechanism underlying the pairing. A Chinese-Korean experimental collaboration carries out element-selective substitutional doping of BaFe${}_{2}$As${}_{2}$ and searches for the pairing symmetry of the resulting iron-based superconductors.

occurring at the upper critical field Hc2, is demonstrated from the �(T) � T near Hc2 and �(T) � T 2 when further increasing field. Large residual linear term �0/T at zero field and the rapid increase of �(H)/T at low field indicate that the superconducting gap in Ce2PdIn8 has nodes, likely d-wave symmetry. The sharp jump of �(H)/T near Hc2 gives evidence for a first-order phase transition at low temperature. These results suggest the existence of a low-temperature-high-field Q phase in Ce2PdIn8, where magnetic order is directly coupled to d-wave superconductivity, as in CeCoIn5.

The in-plane resistivity rho and thermal conductivity kappa of the FeAs-based superconductor KFe2As2 single crystal were measured down to 50 mK. We observe non-Fermi-liquid behavior rho(T) approximately T{1.5} at H{c{2}}=5 T, and the development of a Fermi liquid state with rho(T) approximately T{2} when further increasing the field. This suggests a field-induced quantum critical point, occurring at the superconducting upper critical field H{c{2}}. In zero field, there is a large residual linear term kappa{0}/T, and the field dependence of kappa_{0}/T mimics that in d-wave cuprate superconductors. This indicates that the superconducting gaps in KFe2As2 have nodes, likely d-wave symmetry. Such a nodal superconductivity is attributed to the antiferromagnetic spin fluctuations near the quantum critical point.

The interplay between magnetism and superconductivity has been a central issue in unconventional superconductors. While the dynamic magnetism could be the source of electron pairing, the static magnetism is generally believed to compete with superconductivity. In this sense, the observation of Q phase, the coupled spin-density wave order and superconductivity, in the heavy-fermion superconductor CeCoIn5 is very puzzling. Whether this Q phase origins from the novel Fulde-Ferrel-Larkin-Ovchinnikov state is under hot debate. Here we report the resistivity and thermal conductivity study of a newly discovered heavy-fermion superconductor Ce2PdIn8 down to 50 mK. We find an unusual field-induced quantum critical point at the upper critical field Hc2 and unconventional nodal superconductivity in Ce2PdIn8. The jump of thermal conductivity k(H)/T near Hc2 suggests a first-order-like phase transition at low temperatures. These results mimic the features of the Q phase in CeCoIn5, implying that Ce2PdIn8 is another promising compound to investigate the exotic Q phase and FFLO state. The comparison between CeCoIn5 and Ce2PdIn8 may help to clarify the origin of the Q phase., Comment: 18 pages, 4 figures