Ciri anatomi stip bagi beberapa spesies Davallia (Davalliaceae) di Malaysia (Stipe anatomical characteristics in some Davallia (Davalliaceae) Species in Malaysia)

Kajian anatomi stip telah dijalankan ke atas tujuh spesies Davallia, iaitu D. denticulata, D. divaricata, D. trichomanioides var. trichomanioides, D. trichomanioides var. lorrainii, D. corniculata, D. repens dan D. solida var. solida di Malaysia. Kajian ini melibatkan keratan rentas bahagian stip menggunakan mikrotom gelongsor. Hasil kajian menunjukkan ciri anatomi stip seperti bentuk luaran stip, corak kehadiran sel sklerenkima di bawah epidermis, jenis dan bentuk stel, bilangan berkas vaskular, bilangan lapisan sel parenkima dan juga kehadiran cuping pada keratan rentas stip boleh digunakan untuk pengecaman dan pembezaan spesies. Ciri sepunya bagi genus Davallia ialah kehadiran sel sklerenkima mengelilingi stel dan di bawah lapisan sel epidermis, serta kehadiran sel parenkima berdinding tebal. Banyak ciri diagnostik ditemui dalam kajian ini dan antaranya ialah kehadiran satu cuping pada keratan stip tengah ditemui hanya pada D. trichomanioides var. lorrainii, corak 4 kehadiran sel sklerenkima di bawah epidermis ditemui hanya pada D. repens, corak 3 hanya ditemui pada D. solida var. solida, corak 5 dan 7 hanya ditemui pada D. corniculata, stel jenis dorsiventral protostel bagi D. divaricata dan bagi D. trichomanioides var. trichomanioides pula, kehadiran stel bentuk arka pada stip atas, stip tengah dan juga bawah merupakan ciri diagnostik yang baik untuk pengecaman spesies ini. Hasil kajian ini menunjukkan bahawa ciri anatomi stip mempunyai nilai taksonomi dalam genus Davallia dan boleh digunakan sebagai data sokongan untuk tujuan pengecaman dan pembezaan spesies

Genome-wide association study of breakfast skipping links clock regulation with food timing

Clinical epidemiolog

Multi-messenger Observations of a Binary Neutron Star Merger

International audienceOn 2017 August 17 a binary neutron star coalescence candidate (later designated GW170817) with merger time 12:41:04 UTC was observed through gravitational waves by the Advanced LIGO and Advanced Virgo detectors. The Fermi Gamma-ray Burst Monitor independently detected a gamma-ray burst (GRB 170817A) with a time delay of $\sim 1.7\,{\rm{s}}$ with respect to the merger time. From the gravitational-wave signal, the source was initially localized to a sky region of 31 deg(2) at a luminosity distance of ${40}_{-8}^{+8}$ Mpc and with component masses consistent with neutron stars. The component masses were later measured to be in the range 0.86 to 2.26 $\,{M}_{\odot }$. An extensive observing campaign was launched across the electromagnetic spectrum leading to the discovery of a bright optical transient (SSS17a, now with the IAU identification of AT 2017gfo) in NGC 4993 (at $\sim 40\,{\rm{Mpc}}$) less than 11 hours after the merger by the One-Meter, Two Hemisphere (1M2H) team using the 1 m Swope Telescope. The optical transient was independently detected by multiple teams within an hour. Subsequent observations targeted the object and its environment. Early ultraviolet observations revealed a blue transient that faded within 48 hours. Optical and infrared observations showed a redward evolution over ∼10 days. Following early non-detections, X-ray and radio emission were discovered at the transient’s position $\sim 9$ and $\sim 16$ days, respectively, after the merger. Both the X-ray and radio emission likely arise from a physical process that is distinct from the one that generates the UV/optical/near-infrared emission. No ultra-high-energy gamma-rays and no neutrino candidates consistent with the source were found in follow-up searches. These observations support the hypothesis that GW170817 was produced by the merger of two neutron stars in NGC 4993 followed by a short gamma-ray burst (GRB 170817A) and a kilonova/macronova powered by the radioactive decay of r-process nuclei synthesized in the ejecta