Walk algebras, distinguished subexpressions, and point counting in Kac-Moody flag varieties

We study walk algebras and Hecke algebras for Kac-Moody root systems. Each choice of orientation for the set of real roots gives rise to a corresponding "oriented" basis for each of these algebras. We show that the notion of distinguished subexpression naturally arises when studying the transition matrix between oriented bases. We then relate these notions to the geometry of Kac-Moody flag varieties and Bott-Samelson varieties. In particular, we show that the number of points over a finite field in certain intersections of these varieties is given by change of basis coefficients between oriented bases of the Hecke algebra. Using these results we give streamlined derivations of Deodhar's formula for $R$-polynomials and point-counting formulas for specializations of nonsymmetric Macdonald polynomials $E_\lambda(\mathsf{q},t)$ at $\mathsf{q}=0,\infty$

On the double-affine Bruhat order: the ε = 1 conjecture and classification of covers in ADE type

For any Kac–Moody group G, we prove that the Bruhat order on the semidirect product of the Weyl group and the Tits cone for G is strictly compatible with a Z-valued length function. We conjecture in general and prove for G of affine ADE type that the Bruhat order is graded by this length function. We also formulate and discuss conjectures relating the length function to intersections of “double-affine Schubert varieties”

Kink solitons in DNA

We here examine the nonlinear dynamics of artificial homogeneous DNA chain relying on the plain-base rotator model. It is shown that such dynamics can exhibit kink and antikink solitons of sine-Gordon type. In that respect we propose possible experimental assays based on single molecule micromanipulation techniques. The aim of these experiments is to excite the rotational waves and to determine their speeds along excited DNA. We propose that these experiments should be conducted either for the case of double stranded (DS) or single stranded (SS) DNA. A key question is to compare the corresponding velocities of the rotational waves indicating which one is bigger. The ratio of these velocities appears to be related with the sign of the model parameter representing ratio of the hydrogen-bonding and the covalent-bonding interaction within the considered DNA chain.Comment: 15 pages, 5 figure

Significance of Premature Stop Codons in \u3cem\u3eenv\u3c/em\u3e of Simian Immunodeficiency Virus

The location of the translational termination codon for the transmembrane protein (TMP) varies in three infectious molecular clones of simian immunodeficiency virus from macaques (SIVmac). The SIVmac251 and SIVmac142 infectious clones have premature stop signals that differ in location by one codon; transfection of these DNAs into human HUT-78 cells yielded virus with a truncated TMP (28 to 30 kilodaltons [kDa]). The SIVmac239 infectious clone does not have a premature stop codon in its TMP-coding region. Transfection of HUT-78 cells with this clone initially yielded virus with a full-length TMP (41 kDa). At 20 to 30 days posttransfection, SIVmac239 virus with a 41-kDa TMP gradually disappeared coincident with the emergence of a virus with a 28-kDa TMP. Virus production dramatically increased in parallel with the emergence of a virus with a 28-kDa TMP. Sequence analysis of viral DNAs from these cultures showed that premature stop codons arising by point mutation were responsible for the change in size of the TMP with time. A similar selective pressure for truncated forms of TMP was observed when the SIVmac239 clone was transfected into human peripheral blood lymphocytes (PBL). In contrast, no such selective pressure was observed in macaque PBL. When the SIVmac239 clone was transfected into macaque PBL and the resultant virus was serially passaged in macaque PBL, the virus replicated very well and maintained a 41-kDa TMP for 80 days in culture. Macaque monkeys were infected with SIVmac239 having a 28-kDa TMP; virus subsequently recovered from T4-enriched lymphocytes of peripheral blood showed only the 41-kDa form of TMP. These results indicate that the natural form of TMP in SIVmac is the full-length 41-kDa TMP, just as in human immunodeficiency virus type 1. Viruses with truncated forms of TMP appear to result from mutation and selection during propagation in unnatural human cells

Prospective comparison of microbial culture and polymerase chain reaction in the diagnosis of corneal ulcer.

PURPOSE: To compare polymerase chain reaction (PCR) to microbial culture for the detection and identification of bacterial and fungal pathogens in microbial keratitis. DESIGN: Prospective cohort study. METHODS: A total of 108 consecutive corneal ulcers were cultured and analyzed by PCR using pan-bacterial and pan-fungal primers. PCR products were cloned, sequenced, and compared to culture results using standard bioinformatics tools. RESULTS: Of the 108 samples, 56 were culture-positive, 25 for bacteria and 31 for fungi; 52 were culture-negative. After eliminating false-positive PCR products, 94 of 108 were positive by PCR, 37 for bacteria and 57 for fungi. Nineteen of 25 bacterial culture-positive samples were positive by PCR, and 29 of 31 samples culture-positive for fungi were positive by PCR. The majority of sequenced PCR products matched the positive culture results. Of the 52 culture-negative samples, 46 (88%) yielded pathogen deoxyribonucleic acid (DNA) PCR products, 18 bacterial and 28 fungal. These represented a variety of species, including at least three novel previously uncultured microbes. CONCLUSIONS: PCR detects microbial DNA in the majority of bacterial and fungal corneal ulcers, and identifies potentially pathogenic organisms in a high proportion of culture-negative cases. Yield and concordance with culture are higher for fungal than bacterial ulcers. Practical use of the technique is limited by artefactual amplification of nonpathogenic organisms. PCR may be used as an adjunct to culture to identify potential pathogens in microbial keratitis

PENYULUHAN UPAYA PENCEGAHAN & PENGENDALIAN NYERI PADA PESEPEDA

Sejak masa awal pandemi COVID-19 hingga saat ini, gaya hidup masyarakat mengalami perubahan dalam aspek pekerjaaa, hobi, gaya hidup, pendidikan, dan kesehatan. Olahraga menjadi aktivitas hobi yang populer selama masa pandemi. Selain untuk menjaga kesehatan dan kebugaran, manfaat berolahraga juga untuk mengurangi stress dan bersosialisasi. Ketika pandemi dan diberlakukan ‘pembatasan sosial’ area Jabodetabek, terjadi suatu fenomena, masyarakat senang dan tertarik untuk bersepeda. Penggunaan sepeda meningkat 1000 persen saat pembatasan tersebut di Jabodetabek. Namun peningkatan penggunaan sepeda tidak diimbangi oleh pemahaman mengenai faktor resiko cedera oopenyebab timbulnya nyeri muskuloskeletal yang mengakibatkan gangguan fungsi gerak. Nyeri muskuloskeletal yang tidak diharapkan ini dapat mengganggu produktifitas sehari-hari sehingga beresiko menurunkan kualitas hidup individu. Penyuluhan untuk mencegah nyeri muskuloskeletal pada pesepeda penting dilakukan agar mitra dapat menerapkan langkah-langkah dan teknik pencegahan cedera dan mengoptimalkan manfaat kebugaran bersepeda. Pengabdian ini bertujuan menyelenggarakan penyuluhan bagi para pesepeda untuk langkah-langkah pencegahan di rumah sehingga dapat mengurangi angka kejadian nyeri. Adapun mitra pengabdian adalah komunitas sepeda Purnakarya Tangerang.. Kegiatan berupa penyuluhan terhadap faktor resiko, memberikan langkah-langkah pencegahan sebelum, saat dan  sesudab bersepeda dan strategi pengoptimalan tingkat kebugaran bersepeda. Luaran kegiatan adalah mitra dapat mengelola faktor resiko, langkah-langkah pencegahan, dan optimalisasi manfaat kebugaran olahraga bersepeda.Since the beginning of the COVID-19 pandemic until now, people's lifestyles have experienced changes in the aspects of work, hobbies, lifestyle, education and health. Sports have become a popular hobby activity during the pandemic. In addition to maintaining health and fitness, the benefits of exercise are also to reduce stress and socialize. When there was a pandemic and 'social restrictions' were imposed on the Jabodetabek area, a phenomenon occurred, people were happy and interested in cycling. The use of bicycles increased by 1000 percent during these restrictions in Jabodetabek. However, the increased use of bicycles has not been matched by an understanding of the risk factors for oozing injuries that cause musculoskeletal pain which results in impaired movement function. This unexpected musculoskeletal pain can interfere with daily productivity so that it can reduce the individual's quality of life. Counseling on preventing musculoskeletal pain in cyclists is important so that partners can apply steps and techniques to prevent injuries and optimize the fitness benefits of cycling. This service aims to organize counseling for cyclists on preventive measures at home so as to reduce the incidence of pain. The dedication partner is the Purnakarya Tangerang bicycle community. Activities in the form of counseling on risk factors, providing preventive measures before, during and after cycling and strategies for optimizing cycling fitness levels. The output of the activity is that partners can manage risk factors, preventative measures, and optimize the fitness benefits of cyclin

Molecularly Self-Assembled Nucleic Acid Nanoparticles for Targeted In Vivo siRNA Delivery

Nanoparticles are employed for delivering therapeutics into cells1,2. However, size, shape, surface chemistry and the presentation of targeting ligands on the surface of nanoparticles can affect circulation half-life and biodistribution, cell specific internalization, excretion, toxicity, and efficacy3-7. A variety of materials have been explored for delivering small interfering RNAs (siRNAs) - a therapeutic agent that suppresses the expression of targeted genes8,9. However, conventional delivery nanoparticles such as liposomes and polymeric systems are heterogeneous in size, composition and surface chemistry, and this can lead to suboptimal performance, lack of tissue specificity and potential toxicity10-12. Here, we show that self-assembled DNA tetrahedral nanoparticles with a well-defined size can deliver siRNAs into cells and silence target genes in tumours. Monodisperse nanoparticles are prepared through the self-assembly of complementary DNA strands. Because the DNA strands are easily programmable, the size of the nanoparticles and the spatial orientation and density of cancer targeting ligands (such as peptides and folate) on the nanoparticle surface can be precisely controlled. We show that at least three folate molecules per nanoparticle is required for optimal delivery of the siRNAs into cells and, gene silencing occurs only when the ligands are in the appropriate spatial orientation. In vivo, these nanoparticles showed a longer blood circulation time (t1/2 ∼ 24.2 min) than the parent siRNA (t1/2 ∼ 6 min)

Impact of COVID-19 on liver transplantation in Hong Kong and Singapore: A modelling study

Liver transplantation (LT) activities during the COVID-19 pandemic have been curtailed in many countries. The impact of various policies restricting LT on outcomes of potential LT candidates is unclear. We studied all patients on the nationwide LT waitlists in Hong Kong and Singapore between January 2016 and May 2020. We used continuous time Markov chains to model the effects of different scenarios and varying durations of disruption on LT candidates