Aphthous-like stomatitis of COVID-19 patients

The emerging evidence on oral symptoms that occur in conjunction with coronavirus disease (COVID-19) infection has triggered wide debates on the pathophysiology as well as the potential implications of these manifestations. Hereby, we aim to report according to the CARE guidelines the clinical characteristics of a COVID-19 patient with aphthous-like stomatitis from our clinic. We also performed a literature search in PubMed, Scopus, Google Scholar from inception until 6th of September 2020 with a combination of keywords (COVID-19 OR SARS-CoV-2) AND aphthous. On reviewing the emerging evidence of aphthous lesions in COVID-19, we have found that 14 cases were reported heretofore. Aphthous-like stomatitis as a characteristic condition of immuno-affected patients is a predictable and clinically relevant oral complication of COVID-19 patients. Further studies are warranted to establish its epidemiologic significance and to understand its pathophysiology in COVID-19 patients.

Aspek biologi reproduksi ikan pari blentik Neotrygon kuhlii di perairan Selat Sunda

<p class="BasicParagraph"><strong>ABSTRACT</strong></p><p class="BasicParagraph"> </p><p class="BasicParagraph">Bluespotted stingray fish <em>Neotrygon kuhlii</em> is the important fish economically captured from Sunda Strait. Intensive fishing could decrease bluespotted stingray stock. This study was aimed to know the length-weight, and reproduction characteristic. The reproduction characteristic covered the size of first gonad maturity, the level and also index of gonad maturity of bluespotted stingray fish in Labuan Fishing Dock, Banten. The result showed the equilibrium of length-weight of female fish was about W=0.0007L2,1496. Meanwhile, the male fish was about W=0.0000L2.251. Male fish was better than female fish according their relatively condition factor. Decreasing of the factor condition was caused by feeding habit to grow the reproduction cells. The size of first gonad maturity for the female and male respectively were about 550–799 dan 550–760 mm. The highest level maturity even female or male was on IV achieved in June and Juli 2013. Increasing the index (IKG) was followed by the level of gonad maturity.</p><p class="BasicParagraph"> </p><p class="BasicParagraph">Kata kunci: bluespotted stingray, reproductive characteristic, condition factor, Sunda Strait<strong></strong></p><p class="BasicParagraph"><strong> </strong></p><p class="BasicParagraph"><strong> </strong></p><p class="BasicParagraph"><strong>ABSTRAK</strong></p><p class="BasicParagraph"><strong> </strong></p><p class="BasicParagraph">Ikan pari blentik <em>Neotrygon kuhlii</em> merupakan salah satu sumberdaya ikan ekonomis penting dan sebagai hasil penangkapan di Selat Sunda. Penangkapan yang intensif dapat mengakibatkan penurunan stok ikan pari blentik. Penelitian ini bertujuan untuk mengetahui panjang bobot, dan karakteristik reproduksi. Karaktersitik reproduksi itu sendiri meliputi ukaran pertama kali matang gonad, tingkat kematangan gonad dan indeks kematangan gonad ikan pari blentik di perairan Selat Sunda yang didaratkan di Pelabuhan Perikanan Pantai (PPP) Labuan, Banten. Berdasarkan hubungan panjang bobot ikan pari betina diperoleh persamaan hubungan panjang dan bobot untuk ikan pari blentik betina W=0,0007L2,1496. Sementara itu pada ikan jantan, persamaan hubungan panjang bobot W=0,0000L2,251. Ikan pari blentik jantan mempunyai faktor kondisi yang relatif lebih besar daripada ikan pari betina. Penurunan nilai faktor kondisi disebabkan bagian terbesar dari makanan yang dikonsumsi digunakan untuk perkembangan sel-sel reproduksinya. Kisaran ukuran pertama kali matang gonad ikan pari blentik betina 550–799, sedangkan untuk ikan pari jantan adalah dengan kisaran panjang total tubuh 550–760 mm. Tingkat kematangan gonad tertinggi ikan betina dan jantan (TKG IV) ditemukan pada bulan Juni dan Juli 2013. Indeks kematangan gonad (IKG) ikan pari semakin meningkat seiring dengan meningkatnya TKG.</p><p class="BasicParagraph"><strong> </strong></p><p>Keywords: ikan pari blentik, karakteristik reproduksi, faktor kondisi, Selat Sunda</p>

NOTES ON LIE IDEALS OF SIMPLE ARTINIAN RINGS

Let R be a ring. If we replace the original associative product of R with their canonic Lie product, or [a, b] = ab - ba for every a, b in R, then R would be a Lie ring. With this new product the additive commutator subgroup of R or [R, R] is a Lie subring of R. Herstein has shown that in a simple ring R with characteristic unequal to 2, any Lie ideal of R either is contained in Z(R), the center of R or contains [R, R]. He also showed that in this situation the Lie ring [R, R]/Z[R, R] is simple. We give an alternative matrix proof of these results for the special case of simple artinian rings and show that in this case the characteristic condition can be more restricted.

ON THE DISPERSIVE WAVE DYNAMICS OF 2 × 2 RELAXATION SYSTEMS

We consider hyperbolic conservation laws with relaxation terms. By studying the dispersion relation of the solution of general linearized 2 × 2 hyperbolic relaxation systems, we investigate in detail the transition between the wave dynamics of the homogeneous relaxation system and that of the local equilibrium approximation. We establish that the wave velocities of the Fourier components of the solution to the relaxation system will be monotonic functions of a stiffness parameter φ = εξ, where ε is the relaxation time and ξ is the wave number. This allows us to extend in a natural way the classical concept of the sub-characteristic condition into a more general transitional sub-characteristic condition. We further identify two parameters β and γ that characterize the behavior of such general 2 × 2 linear relaxation systems. In particular, these parameters define a natural transition point, representing a value of φ where the dynamics will change abruptly from being equilibrium-like to behaving more like the homogeneous relaxation system. Herein, the parameter γ determines the location of the transition point, whereas β measures the degree of smoothness of this transition.

Selective Transfer Phenomenon in Copper-Steel Tribological Systems

The paper deals with possibility of selective transfer phenomenon generation in couples consisting of materials of railway traction trolley wire and of pantograph slider material. Some examinations are described concerning tribological characteristics evaluation of above couples. The most characteristic condition of selective transfer phenomenon (known also under the name of “Garkunov effect”) is generation of specific protective metallic layer on friction surfaces of both frictionally cooperating elements that minimize wear and friction resistance. Obtained results led to the conclusion that the selective transfer phenomenon was generated in the model friction pairs examined in the frames of presented work. The magnitude of this phenomenon depended on minimal differences in quantities of additives and impurities in copper.