Updated statistics for crater clusters on Mars

<p>An increasing number of newly formed impact craters on Mars have been detected in the last 15 years. These small craters are normally identified via dark spots in lower resolution images that formed during the impact process, presumably through the removal or disturbance of bright surface material [1]. Later higher resolution images revealed single craters or crater clusters, which form when impactors fragment in the atmosphere, within those halos [1,2]. Due to this detection method, most of the new impact sites found are in dusty regions, which imposes an observational bias [3]. Newly formed clusters consist of two to thousands of individual craters and can be tightly clustered or spread out over hundreds of meters [2]. Since the InSight (Interior Exploration using Seismic Investigations, Geodesy and Heat Transport) mission landed on Mars in 2018 [4], the search for newly formed impact craters has become even more important, because identifying impacts in seismic signals could provide further constraints on both the atmospheric and solid-body effects of impact cratering process on Mars, as well as help place further constraints on the properties of the uppermost layer of the crust. As one of InSight’s mission goals is to estimate the current impact rate on Mars, the seismic detection of impacts is also crucial [4].</p> <p>The aim of this new study is to describe the properties of the complete catalog of known newly formed craters on Mars and examine correlations between different crater cluster properties. We investigated 559 crater clusters and 493 single craters detected between 2008 and 2020 using 25 cm/px HiRISE images. The locations and diameters were noted for each single crater, as well as for every individual crater within a cluster down to 1 m diameter. This was done using ArcMap (ArcGIS) software with the three-point method of the CraterTools add-in [5]. We describe the cluster characteristics, such as the number of craters within a cluster, largest crater in a cluster, cluster effective diameter, cluster dispersion, elevation of the impact sites, and the variation in sizes of craters within a cluster.</p> <p>More than half of the new impact sites form as clusters. We did not find any differences between the spatial distribution of single and crater clusters across Mars. The mapped crater clusters from this study consist of 2 to 2334 individual craters. More than half of all clusters (58%) consist of 10 craters or less. Crater clusters containing more than 100 craters are rare. With regard to the sizes of craters within crater clusters, we found that for highly populated clusters, the majority of craters are very small, and clusters with few craters have a tendency for craters that are more equal in size. Clusters having large effective diameters contain more equally sized craters. Our results show the full range of parameter spaces that are possible for cluster properties, which can help validate theoretical atmospheric fragmentation models.</p> <p><strong>References:</strong></p> <p>[1] Malin M. C. et al. (2006) Science, 314, 1573-1577.</p> <p>[2] Daubar I. J. et al. (2019) JGR, 124, 958-969.</p> <p>[3] Daubar I. J. et al. (2013) Icarus, 225, 506-516.</p> <p>[4] Banerdt B. W. et al. (2020) Nature, 13, 183-189.</p> <p>[5] Kneissl T. et al. (2011) Planet. Space Sci., 59, 1243-1254.</p>

Management of Mucocele of the Glands of Blandin-Nuhn With a High-Intensity Laser: A Case Report

Introduction: The glands of Blandin–Nuhn are mucous and serous salivary glands situated on both sides of the midline of the ventral surface of the tongue. In this area, a mucocele generally results from trauma. The diagnosis of mucoceles is based on clinical and histopathological examinations and the recommended treatment is surgical excision. Case Report: This report describes a case of mucocele of the glands of Blandin-Nuhn (MGBN) affecting a 20-year-old male. Oval-shaped swelling with a smooth and bright surface of soft consistency was observed on the ventral surface of the individual’s tongue. The diagnostic hypothesis was mucocele. Surgical excision was performed in a single session with a diode laser. A histopathological examination revealed mucus extravasating into connective tissue, with foamy macrophages and granulation tissue. Conclusion: The high-intensity laser was a safe and effective tool for treating MGBN. No need for a suture, minimal or no intraoperative bleeding, and a minimal report of pain and edema by the patient were observed. A diode laser may be a helpful tool because it is less invasive and it is safe and effective.

Understanding Sandfly Sampling Methods: The Sticky Traps are attraction-based and not interceptive sampling tools of Phlebotomus orientalis

Background : It is generally assumed that sticky traps are interceptive sandfly sampling methods, although no previous experimental evidence has supported this assumption. In this study, we test this assumption experimentally for Phlebotomus orientalis , the principal vector of visceral leishmaniasis in East Africa, and provide an explanation for why their collection is highly male-biased. Methods: Three field experiments were carried out in March 2016-June 2019, in Gedarif state, eastern Sudan. In a first experiment, we compared numbers of P. orientalis caught with sticky traps made of black, red, transparent, white, yellow, green and blue A4 size papers that were set simultaneously at different lunar light conditions. In a second and a third experiments, we compared numbers of P. orientalis captured on sticky traps placed side by side horizontally or vertically on the ground or horizontally on a stool. We also made observations on mating behaviour of sandflies following their landing on un-sticky papers placed on the ground. Results: Phlebotomus orientalis showed significant attraction to white, yellow and transparent traps; with negligible numbers caught on the black and the red traps. Similarly, significantly higher numbers of P. orientalis were attracted to the horizontal traps, resulting in 8-fold increase in their yield as compared to the vertical traps. Placing the traps on the stools resulted in significant reduction of this attraction. In contrast to the sticky traps that captured only very few females, our observations indicated that when male sandflies land on un-sticky white paper they successfully lure females and copulate with them. Conclusion: The study demonstrated that for P. orientalis, sticky traps are more attractant-based than interception-based sampling tools and supports the notion that males of this sandfly species probably utilize the bright surface of the papers of the traps to perform mating rituals to attract the females for copulation. However, their pre-mature death in the sticky oil hampers the completion of these rituals and thus the result in failure of the attraction of the females. The findings of the study have important implications for optimization of the ST design for vector surveillance purpose and understanding the behaviour of P. orientalis .

Simulated mass measurements of the young planet K2-33b

ABSTRACT In this paper, we carry out simulations of radial velocity (RV) measurements of the mass of the 8–11 Myr Neptune-sized planet K2-33b using high-precision near-infrared velocimeters like SPIRou at the Canada–France–Hawaii Telescope. We generate an RV curve containing a planet signature and a realistic stellar activity signal, computed for a central wavelength of 1.8 µm and statistically compatible with the light curve obtained with K2. The modelled activity signal includes the effect of time-evolving dark and bright surface features hosting a 2 kG radial magnetic field, resulting in an RV signal of semi-amplitude ∼30 m s−1. Assuming a 3-month visibility window, we build RV time series including Gaussian white noise from which we retrieve the planet mass while filtering the stellar activity signal using Gaussian process regression. We find that 35/50 visits spread over three consecutive bright-time runs on K2-33 allow one to reliably detect planet RV signatures of, respectively, 10 and 5 m s−1 at precisions >3σ. We also show that 30 visits may end up being insufficient in some cases to provide a good coverage of the stellar rotation cycle, with the result that the planet signature can go undetected or the mass estimation be plagued by large errors.

Large regional shortwave forcing by anthropogenic methane informed by Jovian observations

Recently, it was recognized that widely used calculations of methane radiative forcing systematically underestimated its global value by 15% by omitting its shortwave effects. We show that shortwave forcing by methane can be accurately calculated despite considerable uncertainty and large gaps in its shortwave spectroscopy. We demonstrate that the forcing is insensitive, even when confronted with much more complete methane absorption spectra extending to violet light wavelengths derived from observations of methane-rich Jovian planets. We undertake the first spatially resolved global calculations of this forcing and find that it is dependent on bright surface features and clouds. Localized annual mean forcing from preindustrial to present-day methane increases approaches +0.25 W/m2, 10 times the global annualized shortwave forcing and 43% of the total direct CH4forcing. Shortwave forcing by anthropogenic methane is sufficiently large and accurate to warrant its inclusion in historical analyses, projections, and mitigation strategies for climate change.

Temperature Rise Real-Time Measurement of Metro Tread Based on the Multi-Sensor Fusion and Online Compensation Method

To study the temperature rise of the metro wheel tread, the simulation is conducted, finding that the highest temperature emerges in the tread area during the braking process, up to 350 °C. The range of temperature measurement should include 0∼350 °C. The temperature rise of the tread surface and the temperature near the side of the wheel tread tend to be consistent after the braking. The temperature measurement on the side of the wheel can provide a reference for the tread temperature measurement. Then several kinds of temperature sensors used for testing the tread temp are introduced, the accuracy and influencing factors of the measurement of the tread surface temperature sensor was analyzed. For the temperature measurement of wheel tread, featuring bright surface emission, low and unstable emissivity, a real-time temperature test method with multi-sensor compensation and data fusion is proposed and a more realistic curve of the tread temperature is obtained. Taking the actual line pure-air brake condition as an example, the above method is used to measure the temperature of tread surface. The results show that the measurement accuracy of multi-sensor data compensation and fusion is better than that of using the single infrared thermometer method, up by 15%; The law of temperature rise is consistent with that of transient simulation. reflecting that this testing method can offer important references to the real-time measurement of tread temperature.