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Global warming and anticipated increase in rainfall frequency and magnitude are linked to enhanced rockfall activity worldwide. Arid environments, which currently receive limited amount of annual rainfall, will be particularly subject to frequent and unpredictable rockfall activity that can substantially jeopardize human lives and infrastructures. The main scope of this study is to assess the rockfall hazards in Thawr Mountain and Al-Azyziah district, western Saudi Arabia, using integrated field, geological, climatological and remote sensing datasets and modeling. Our findings indicated that: (1) there are general increasing trends of average annual precipitation and temperature for the period between 2009 and 2019, (2) inspection of multi-temporal satellite images between 2003 and 2017 showed rapid urban expansion, mainly through modification of hillslopes for urban development, which is expected to pose critical consequences on slope instability, (3) field investigations attributed rockfall activity to weathered exfoliated granodiorite hillslopes with abundant tension cracks and steep slopes, (4) slope degrees reached 79° with a general slope direction toward the urbanized areas, and (5) the rockfall motion was simulated along six profiles with dynamic urban areas along the termination of each profile, which showed that several blocks along the six profiles can reach the profile termination with medium intensity rockfall activity and kinetic energy ranges between 50 and 80 kj. The reported rockfall motion can threaten lives, houses and infrastructures. Therefore, protective precautions were suggested to prevent and mitigate the impact of rockfall activity along the studied profiles and similar areas in the mountainous western Arabian Peninsula. [ABSTRACT FROM AUTHOR]

This paper presents the first results of a new Arar-magnetometer station located (Geographic Coordinates: 30°50.2′N, 41°11.3′E) at Northern Border University in Saudi Arabia. The geomagnetic response detected by the station during a moderate magnetic storm of April 20, 2018 is examined as an initial study. The X-component of the magnetic field measured by the station showed a prompt increase coincident with the Sudden Storm Commencement (SSC) measured by the ACE satellite. The three components of the measured magnetic field were compared to the measured data from the nearest four INTERMAGNET stations as a test. The high rate of magnetic field digital data system of Arar-Magnetometer station with sampling rate of 0.1 s allowed us to study the geomagnetic pulsation at the northern region of the Arabian Peninsula for the first time, which will promote the research of space weather monitoring in that area. [ABSTRACT FROM AUTHOR]

• Seven different plant growth regulator combinations were studied for the optimum production of secondary metabolites. • Eleven different secondary metabolites were identified in the obtained extracts. • More than 4 folds increase in some secondary metabolite concentrations were detected in the calli extracts compared to the plant parts. • The antimicrobial activities against six microorganisms and the cytotoxic effects against two cancer cell lines for the obtained calli extracts were evaluated. • The biological activities were noticeably enhanced for the obtained calli extracts. Lepidium sativum L. family Brassicaceae (Cruciferae) is one of the most recognized Lepidium species in the folk medicine of Africa and the middle east. Its English common name is Garden cress and known as Hab Al-Rashad in north Africa and the Arabian Peninsula. It is well known for a wide range of biological activities and a complex phytochemical composition. The current study investigates tissue culture protocols for L. sativum. For static culture initiation, Murashige and Skooge (MS) as a basal medium for L. sativum leaves was employed. Suspension cultures were initiated from leaf explant calli of L. sativum using media supplemented with various combinations of hormonal supply of 2,4 dichloro phenoxy acetic acid (2,4-D), indole-3- acetic acid (IAA), 1-naphthyl acetic acid (NAA), and adenine. Liquid chromatography/mass spectroscopy (LC/MS) analysis was performed on the ethanolic extracts of plant parts and the produced calli. The LC/MS analysis revealed the presence of eleven secondary metabolites with varying concentrations. The identified compounds are apigenin, quercetin, kaempferol, luteolin and 7-hydroxy-4′,5,6-trimethoxyisoflavone, sinapic acid, chlorogenic acid, p -coumaric acid, ascorbic acid, α-tocopherol and 6-prenylnaringenin. Antimicrobial and cytotoxic activities were evaluated for the calli extracts. In general, superior activities were identified for the produced calli extracts when compared to plant parts' extracts. [ABSTRACT FROM AUTHOR]

Observing Earth from the space is key for monitoring land-surface dynamics and probing near-surface geomorphic and geological features, including those obscured by sand sheets/dunes and human activity. The hyper-arid area of the Arabian Peninsula was selected for detecting and extracting obscure paleohydrological systems and modeling the spatio-temporal dynamics of sand dunes using synthetic aperture radar (SAR) and optical high-resolution remote sensing images. Interferometric synthetic aperture radar (InSAR) coherence change detection (CCD) using Sentinel-1 imagery was performed, revealing subtle changes in the surficial landforms of the study area. These images also discriminated between active and inactive geomorphic features. In addition, low-frequency L-band Advanced Land Observing Satellite/Phased Array type L-band Synthetic Aperture Radar (ALOS/PALSAR) and Shuttle Radar Topography Mission (SRTM) data revealed the details of paleochannels in the basins that drain into the Arabian Gulf. These ephemeral rivers are the source of sand that was later reshaped into dunes by aeolian processes. The results also revealed that the morphology and extension of dunes were clearly influenced by topography, slope, and wind velocity and direction, rather than human activities. Knowledge gained by exploring desert features is essential for planning settlements and development, and integrated approaches using a variety of remote sensing datasets are key for enhancing Earth observation across a range of spatial and temporal scales. • InSAR quantified the land surface changes in spatio-temporal scale. • L-band ALOS/PALSAR obscured the buried paleohydrologic systems. • High image resolution of Sentinel-1&2 and Google Earth well successfully defined the dynamic of sand dunes. [ABSTRACT FROM AUTHOR]