Constraints on the thermal evolution of Venus inferred from Magellan data

The impact craters with diameters from 1.5 to 280 km compiled from Magellan observations indicate that the crater population on Venus has a completely spatially random distribution and the size/density distribution of craters with diameters greater than or equal to 35 km is consistent with a 'production' population with an age of 500 plus or minus 250 m.y. The similarity in size distribution from area to area indicates that the crater distribution is independent of crater size. Also, the forms of the modified craters are virtually identical to those of the pristine craters. These observations imply that Venus reset its cratering record by global resurfacing 500 m.y. ago, and resurfacing declined relatively fast. The fact that less than 40 percent of all craters have been modified and that the few volcanically embayed craters are located on localized tectonic regions indicate that only minor and localized volcanism and tectonism have occurred since the latest vigorous resurfacing event approximately 500 m.y. ago and the interior of Venus has been solid and possibly colder than Earth's. This is because the high-temperature lithosphere of Venus would facilitate upward ascending of mantle plumes and result in extensive volcanism if the venusian upper mantle were as hot as or hotter than Earth's. Therefore, the present surface morphology of Venus may provide useful constraints on the pattern of that vigorous convection, and possibly on the thermal state of the venusian mantle. We examine this possibility through numerical calculations of three-dimensional thermal convection models in a spherical shell with temperature- and pressure-dependent Newtonian viscosity, temperature-dependent thermal diffusivity, pressure-dependent thermal expansion coefficient, and time-dependent internal heat production rate solar magnitude

Liquid Film Falling on Horizontal Circular Cylinders

The objective of this study is to investigate experimentally and numerically the behaviour of liquid film flow over horizontal cylinders. Numerical simulations are performed using a CFD code (FLUENT) for 2D configurations with one, two and three cylinders. The numerical results have been compared with the present experimental results as well as those from the literature. The flow modes and film thickness are reported for the Reynolds numbers range of 400 and 3200. The effect of cylinder separation on the film flow is investigated

Formulasi dan Evaluasi Mikroemulgel dari Ekstrak Daun Sirsak (Annona Muricata L.)

Staphylococcus aureus merupakan salah satu bakteri penyebab jerawat. Salah satu tanaman yang berpotensi sebagai antijerawat adalah daun sirsak. Penelitian ini dilakukan untuk mengembangkan formulasi ekstrak daun  sirsak dan evaluasinya, sehingga memiliki stabilitas yang baik. Penelitian ini diawali dengan mengekstraksi daun sirsak menggunakan metode maserasi, kemudian dilakukan fermentasi untuk membandingkan konsentrasi hambat minimum yang lebih efektif sebagai antibakteri Staphyloccoccus aureus. Setelah itu, dibuat 9 formula mikroemulsi dengan variasi konsentrasi dan jenis kosurfaktan yaitu Tegocare® dan Plantacare®. Pemilihan formula mikroemulsi terbaik dipilih berdasarkan evaluasi secara organoleptik. Terhadap mikroemulsi terbaik dilakukan karakterisasi lainnya seperti pengujian freeze and thaw, uji sentrifugasi dan uji TEM (Transmission Electron Microscopy). Evaluasi sediaan mikroemulgel meliputi organoleptik, pH, viskositas, homogenitas, dan daya sebar selama penyimpanan 28 hari, serta uji panelis. Hasil menunjukkan bahwa tidak ada perbedaan signifikan (sig > 0,05) antara ekstrak fermentasi dan nonfermentasi, sehingga ekstrak nonfermentasi digunakan dalam formulasi dengan konsentrasi 10 mg/ml. Mikroemulsi dengan kosurfaktan Plantacare® 10% merupakan formula mikroemulsi terpilih. Pada pengujian freeze and thaw, mikroemulsi stabil sampai siklus kelima, sedangkan pada pengujian TEM mikroemulsi memiliki ukuran partikel sebesar 50,0 nm. Mikroemulsi terpilih diinkorporasi ke dalam 3 formula basis gel (Viscolam®) dengan variasi konsentrasi 8% - 10%. Dari hasil analisis menggunakan ANOVA, nilai pH pada ketiga formula tersebut tidak konstan (sig < 0,05), sedangkan untuk nilai viskositas hanya formula II (konsentrasi 9%) yang konstan pada nilai sig > 0,05

Penggunaan Modul Berbasis Kontekstual Terhadap Hasil Belajar Fisika Peserta Didik Pada Pokok Bahasan Hukum Newton Kelas VIII Mts. Madani Alauddin Paopao

Tujuan penelitian ini adalah menegetahui apakah modul fisika berbasis kontekstual dapat digunakan sebagai alternatif dalam proses pembelajaran pada kelas VIII MTs. Madani Alauddin Paopao Kab. Gowa. Populasi dalam penelitian ini adalah seluruh peserta didik kelas VIII MTs. Madani Alauddin Paopoa Kab. Gowa yang berjumlah 95 peserta didik. Dengan menggunakan teknik Random Class diperoleh sampel satu kelas dengan jumlah peserta didik sebanyak 31 orang. Instrumen penelitian yang digunakan yaitu kuesioner dan tes hasil belajar. Teknik analisis data yang digunakan yaitu analisis data statistik deskriptif dan inferensial. Berdasarkan analisis deskriptif untuk respons peserta didik terhadap modul fisika berbasisis kontekstual menunjukkan bahwa 97% dari jumlah keseluruhan peserta didik memberi respons positif dan sangat positif dengan rerata penilaian berada pada kategori 4,0 (senang). Tes hasil belajar peserta didik mencapai nilai rata-rata 83,55, berada pada kategori tinggi melebihi standar KKM yakni 75. Berdasarkan Hasil uji normalitas data diperoleh nilai signifikan 0,395, sehingga nilai Sig > α (0,05) maka data hasil belajar berasal dari populasi berdistribusi normal. Berdasarkan hasil uji hipotesis diperoleh thitung = 4,972 dan nilai ttabel = 1,697. Karena nilai thitung > ttabel maka H0 ditolak sehingga Ha diterima. Dengan demikian, hasil belajar sesudah diajarkan dengan menggunakan modul fisika berbasis kontekstual telah mencapai standar KKM

Re-Imagining Machine Learning in Dental Research: A Lesson Learned from the COVID-19 Pandemic

At this time, humankind is experiencing on a global scale a frightening infectious disease caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). As of September 25, 2020, more than 32.3 million cases have been reported in 188 countries, resulting in more than 984,000 official reported deaths.[1],[2] During the course of human history, there have been several pandemics, for example, plague and smallpox. However, one of the main differences between COVID-19 and previous pandemics is the availability of computer-based technologies. Paralleling the global growth of COVID-19, studies using computer-based technologies have emerged (e.g., machine learning) to fight against SARS-CoV-2

Do Open Access Dental Articles Enjoy Higher Altmetric Attention Scores, Twitter, Facebook, News, Wikipedia, Blog mentions, Mendeley Readers and Citations?

In order to access articles published in conventional (non-open access) journals, scientists must utilize tools such as subscriptions, site licenses or pay-per-view charges. In contrast, open access articles can be accessed without financial, legal or technical barriers. A large-scale study estimated that at least 28% of the academic literature is open access (19 million in total) and that this percentage is growing.[1] A recent survey showed an open access rate in field of dentistry at 45.8%.[2] It has been demonstrated that open access articles had 8% to 40% higher citations compared to non-open access articles; this has been termed, “open access citation advantage”.[3],[4],[5

Optimum range of angle tracking radars: a theoretical computing

In this paper, we determine an optimal range for angle tracking radars (ATRs) based on evaluating the standard deviation of all kinds of errors in a tracking system. In the past, this optimal range has often been computed by the simulation of the total error components; however, we are going to introduce a closed form for this computation which allows us to obtain the optimal range directly. Thus, for this purpose, we firstly solve an optimization problem to achieve the closed form of the optimal range (Ropt.) and then, we compute it by doing a simple simulation. The results show that both theoretical and simulation-based computations are similar to each other

Uptake of Neisserial autotransporter lipoprotein (NalP) promotes an increase in human brain microvascular endothelial cell metabolic activity

Neisseria meningitidis is normally a human nasopharyngeal commensal but is also capable of causing lifethreatening sepsis and meningitis. N. meningitidis secretes several virulence-associated proteins including Neisserial autotransporter lipoprotein (NalP), an immunogenic, type Va autotransporter harboring an S8-family serine endopeptidase domain. NalP has been previously characterized as a cell-surface maturation protease which processes other virulence-associated meningococcal surface proteins, and as a factor contributing to the survival of meningococci in human serum due to its ability to cleave complement factor C3. Here, recombinant NalP (rNalP) fragments were purified and used to investigate the interaction of NalP with host cells. Flow cytometry and confocal microscopy demonstrated binding and uptake of rNalP into different human cell types. High-resolution microscopy confirmed that internalized rNalP predominantly localized to the perinuclear region of cells. Abolition of rNalP protease activity using site-directed mutagenesis did not influence uptake or subcellular localization, but inactive rNalP (rNalPS426A) was unable to induce an increase in human brain microvascular endothelial cell metabolic activity provoked by proteolytically-active rNalP. Our data suggests a more complex and multifaceted role for NalP in meningococcal pathogenesis than was previously understood which includes novel intra-host cell functions