Simulation of a Casimir-like effect in a granular pile with avalanches

Using a modified Bak-Tang-Wiesenfeld model for sand piles, we simulate a Casimir-like effect in a granular pile with avalanches. Results obtained in the simulation are in good agreement with results previously acquired experimentally: two parallel walls are attracted to each other at small separation distances, with a force decreasing with increasing distance. In the simulation only, at medium distances a weak repulsion exists. Additionally, with the aim of avalanche prevention, the possibility of suppressing self-organized criticality with an array of walls placed on the slope of the pile is investigated, but the prevention effect is found to be negligible. © 2011 American Physical Society

An investigation of combined free and forced convection heat transfer in a horizontal, isothermal tube

M.S.Calvin C. Olive

Shale Gas: Opportunities and Challenges between Mexico and the United States

Would it be it better for Mexico to remain a net importing partner of natural gas from the United States or to encourage its own Mexican Gas Revolution? Mexico has an estimate 545 trillion cubic feet (Tcf) of shale natural gas reserves, and trillions of additional cubic feet of conventional reserves. Nevertheless, the country has remained a net importer of natural gas due to underdevelopment. Meanwhile, shale gas production on the other side of the border has increased significantly over the past decade, causing United States gas prices to drop. Due to its close proximity to the major shale field development in South and West Texas, Mexico is particularly well-positioned to take advantage of unconventional extraction techniques and apply them in Mexico. This article examines the legal, economic, and environmental challenges and opportunities of the unconventional production landscape in Mexico in order to propose effective solutions by which Mexico can take advantage of its own resources

Can the Philippines' Human Resource Base Meet the Challenge of a Liberalized Financial Sector?

Is the Philippines ready to face foreign competition in the financial sector? Does it have enough supply of professionals who are capable of meeting the human resource requirements of domestic and foreign financial corporations in this kind of liberalized environment? Professor Tullao seeks to provide the answers in this Policy Notes.financial sector, financial liberalization, human resource development

From circular paths to elliptic orbits: A geometric approach to Kepler's motion

The hodograph, i.e. the path traced by a body in velocity space, was introduced by Hamilton in 1846 as an alternative for studying certain dynamical problems. The hodograph of the Kepler problem was then investigated and shown to be a circle, it was next used to investigate some other properties of the motion. We here propose a new method for tracing the hodograph and the corresponding configuration space orbit in Kepler's problem starting from the initial conditions given and trying to use no more than the methods of synthetic geometry in a sort of Newtonian approach. All of our geometric constructions require straight edge and compass only.Comment: 9 pages, 4 figure

Listen to the Voices: A Reflection on How 2020 and COVID-19 Have Affected Lives

Throughout the last few months of 2019, stories of a new and deadly virus were on every news channel around the world. Many Americans saw it as foreign news, others worried about the virus’ spread, and some felt that it would be contained quickly never making it past the Atlantic or Pacific. By March of 2020, COVID-19 made its way to the United States, forcing a new normal of quarantining, remote-learning/teaching, and teleworking. Graduate students and educators of Professional Opportunities Supporting Scholarly Engagement (POSSE), a College of Education program focused on research and contributing to the educational field of discourse, came together with a notion and a desire to provide support during this challenging time. Using a Google form questionnaire, POSSE reached out to as many people throughout the United States and the world to share their experiences with the changes, good and bad, over the past year

The enzymes LSD1 and Set1A cooperate with the viral protein HBx to establish an active hepatitis B viral chromatin state

Indexación: Web of ScienceWith about 350 million people chronically infected around the world hepatitis B is a major health problem. Template for progeny HBV synthesis is the viral genome, organized as a minichromosome (cccDNA) inside the hepatocyte nucleus. How viral cccDNA gene expression is regulated by its chromatin structure; more importantly, how the modulation of this structure impacts on viral gene expression remains elusive. Here, we found that the enzyme SetDB1 contributes to setting up a repressed cccDNA chromatin state. This repressive state is activated by the histone lysine demethylase-1 (LSD1). Consistently, inhibiting or reducing LSD1 levels led to repression of viral gene expression. This correlates with the transcriptionally repressive mark H3K9 methylation and reduction on the activating marks H3 acetylation and H3K4 methylation on viral promoters. Investigating the importance of viral proteins we found that LSD1 recruitment to viral promoters was dependent on the viral transactivator protein HBx. Moreover, the histone methyltransferase Set1A and HBx are simultaneously bound to the core promoter, and Set1A expression correlates with cccDNA H3K4 methylation. Our results shed light on the mechanisms of HBV regulation mediated by the cccDNA chromatin structure, offering new therapeutic targets to develop drugs for the treatment of chronically infected HBV patients.http://www.nature.com/articles/srep2590

Construction of a Multiplex Promoter Reporter Platform to Monitor Staphylococcus aureus Virulence Gene Expression and the Identification of Usnic Acid as a Potent Suppressor of psm Gene Expression

As antibiotic resistance becomes phenomenal, alternative therapeutic strategies for bacterial infections such as anti-virulence treatments have been advocated. We have constructed a total of 20 gfp-luxABCDE dual-reporter plasmids with selected promoters from S. aureus virulence-associated genes. The plasmids were introduced into various S. aureus strains to establish a gfp-lux based multiplex promoter reporter platform for monitoring S. aureus virulence gene expressions in real time to identify factors or compounds that may perturb virulence of S. aureus. The gene expression profiles monitored by luminescence correlated well with qRT-PCR results and extrinsic factors including carbon dioxide and some antibiotics were shown to suppress or induce the expression of virulence factors in this platform. Using this platform, sub-inhibitory ampicillin was shown to be a potent inducer for the expression of many virulence factors in S. aureus. Bacterial adherence and invasion assays using mammalian cells were employed to measure S. aureus virulence induced by ampicillin. The platform was used for screening of natural extracts that perturb the virulence of S. aureus and usnic acid was identified to be a potent repressor for the expression of psm.published_or_final_versio