Flattened Stirling Permutations

Recall that a Stirling permutation is a permutation on the multiset $\{1,1,2,2,\ldots,n,n\}$ such that any numbers appearing between repeated values of $i$ must be greater than $i$. We call a Stirling permutation ``flattened'' if the leading terms of maximal chains of ascents (called runs) are in weakly increasing order. Our main result establishes a bijection between flattened Stirling permutations and type $B$ set partitions of $\{0,\pm1,\pm2,\ldots,\pm (n-1)\}$, which are known to be enumerated by the Dowling numbers, and we give an independent proof of this fact. We also determine the maximal number of runs for any flattened Stirling permutation, and we enumerate flattened Stirling permutations with a small number of runs or with two runs of equal length. We conclude with some conjectures and generalizations worthy of future investigation.Comment: 15 pages, 1 figure, 2 tabl

Effect of Compost Quality and Microbial Population Density of Composts on the Suppressiveness of Pythium myriotylum, Causal Agent of Cocoyam (Xanthosoma sagittifolium) Root Rot Disease in Cameroon

The effect of eight compost types made from four different grass species mixed with poultry and pig manure and microbial population in compost were evaluated on the suppressiveness of the root rot disease on cocoyam. The experimental layout was a complete randomized design with five replicates conducted in a screen house in the Faculty of Agronomy and Agricultural Sciences, University of Dschang. Compost was used in the ratio of 1:1 by weight (2kg compost: 2kg soil/plant). It was inoculated 48 hours before planting to enable compost-pathogen interaction. Compost microbial populations were estimated using dilution plating with appropriate media (tryptic soil agar, TSA) for Heterotrophic bacteria and Actinomycetes isolation agar for Actinomycetes respectively. The physicochemical properties (pH-H2O, CEC, N, K, Na, Mg and Ca) of compost were determined and analysed. Disease incidence and severity was significantly (

Dwarf-Dwarf Interactions Can Both Trigger and Quench Star Formation

It is exceedingly rare to find quiescent low-mass galaxies in the field. UGC5205 is an example of such a quenched field dwarf ($M_\star\sim3\times10^8M_\odot$). Despite a wealth of cold gas ($M_{\rm HI}\sim 3.5 \times 10^8 M_\odot$) and GALEX emission that indicates significant star formation in the past few hundred Myr, there is no detection of H$\alpha$ emission -- star formation in the last $\sim 10$ Myr -- across the face of the galaxy. Meanwhile, the near equal-mass companion of UGC5205, PGC027864, is starbursting ($\rm EW_{\rm H\alpha}>1000$ Angstrom). In this work, we present new Karl G. Jansky Very Large Array (VLA) 21 cm line observations of UGC5205 that demonstrate that the lack of star formation is caused by an absence of HI in the main body of the galaxy. The HI of UGC5205 is highly disturbed; the bulk of the HI resides in several kpc-long tails, while the HI of PGC027864 is dominated by ordered rotation. We model the stellar populations of UGC5205 to show that, as indicated by the UV-H$\alpha$ emission, the galaxy underwent a coordinated quenching event $\sim\!100-300$ Myr ago. The asymmetry of outcomes for UGC5205 and PGC027864 demonstrate that major mergers can both quench and trigger star formation in dwarfs. However, because the gas remains bound to the system, we suggest that such mergers only temporarily quench star formation. We estimate a total quenched time of $\sim 560$ Myr for UGC5205, consistent with established upper limits on the quenched fraction of a few percent for dwarfs in the field.Comment: 20 pages, 13 figures. Accepted to Ap

A qualitative analysis of factors influencing antiretroviral adherence among persons living with <scp>HIV</scp> in Ghana

Adherence to antiretroviral therapy (ART) remains an important factor in HIV prevention and treatment efforts. We explored the individual and environmental factors influencing antiretroviral adherence among PLWH in Ghana. This study used 20 semi-structured in-depth interviews and three focus group discussions (FGD) involving 29 PLWH attending one of three antiretroviral clinics. Thematic analysis covered experiences of PLWH clinic visits, knowledge, attitudes, self-efficacy related to ART adherence, psychological wellbeing and stigma. The findings suggest that both individual and environmental factors including treatment outcome, coping skills, disclosure, self-regulation, healthcare-provider interaction, family and partner support, organization of ART clinics, stigma, and transportation cost influenced treatment adherence. Interventions that empower PLWH and reduce HIV-related stigma in the community will most likely support antiretroviral adherence. Please refer to the Supplementary Material section to find this article's Community and Social Impact Statement

The Effect of Macromolecular Crowding, Ionic Strength and Calcium Binding on Calmodulin Dynamics

The flexibility in the structure of calmodulin (CaM) allows its binding to over 300 target proteins in the cell. To investigate the structure-function relationship of CaM, we combined methods of computer simulation and experiments based on circular dichroism (CD) to investigate the structural characteristics of CaM that influence its target recognition in crowded cell-like conditions. We developed a unique multiscale solution of charges computed from quantum chemistry, together with protein reconstruction, coarse-grained molecular simulations, and statistical physics, to represent the charge distribution in the transition from apoCaM to holoCaM upon calcium binding. Computationally, we found that increased levels of macromolecular crowding, in addition to calcium binding and ionic strength typical of that found inside cells, can impact the conformation, helicity and the EF hand orientation of CaM. Because EF hand orientation impacts the affinity of calcium binding and the specificity of CaM's target selection, our results may provide unique insight into understanding the promiscuous behavior of calmodulin in target selection inside cells.Comment: Accepted to PLoS Comp Biol, 201

Dwarf–Dwarf Interactions Can Both Trigger and Quench Star Formation

It is exceedingly rare to find quiescent low-mass galaxies in the field at low redshift. UGC 5205 is an example of such a quenched field dwarf ( M _⋆ ∼ 3 × 10 ^8 M _⊙ ). Despite a wealth of cold gas ( M _HI ∼ 3.5 × 10 ^8 M _⊙ ) and UV emission that indicates significant star formation in the past few hundred megayears, there is no detection of H α emission—star formation in the last ∼10 Myr—across the face of the galaxy. Meanwhile, the near equal-mass companion of UGC 5205, PGC 027864, is starbursting (which has an H α equivalent width > 1000 Å). In this work, we present new Karl G. Jansky Very Large Array 21 cm line observations of UGC 5205, showing that the lack of star formation is caused by an absence of H i in the main body of the galaxy. The H i of UGC 5205 is highly disturbed; the bulk of the H i resides in several-kiloparsec–long tails, while the H i of PGC 027864 is dominated by ordered rotation. We model the stellar populations of UGC 5205 to show that, as indicated by the UV and H α emission, the galaxy underwent a coordinated quenching event ∼100–300 Myr ago. The asymmetry of outcomes for UGC 5205 and PGC 027864 demonstrate that major mergers can both quench and trigger star formation in dwarfs. However, because the gas remains bound to the system, we suggest that such mergers only temporarily quench star formation. We estimate a total quenched time of ∼560 Myr for UGC 5205, consistent with established upper limits on the quenched fraction of a few percent for dwarfs in the field

Prevalence of Toxoplasma gondii infection in animals of the Arabian Peninsula between 2000–2020: A systematic review and meta‐analysis

Abstract Background Toxoplasma gondii (T. gondii) is a zoonotic parasite that can be transmitted from animals to humans, with felids acting as its definitive host. Thus, understanding the epidemiology of this parasite in animal populations is vital to controlling its transmission to humans as well as to other animal groups. Objectives This systematic review and meta‐analysis aims to summarise and analyse reports of T. gondii infection in animal species residing in the Arabian Peninsula. Methods : It was conducted in accordance with the Preferred Reporting Items for Systematic Reviews and Meta‐Analyses (PRISMA), with relevant studies being retrieved from MEDLINE/PubMed, Scopus, Cochrane Library, Google Scholar and ScienceDirect. All articles published in Arabic or English languages between January 2000 and December 2020 were screened for eligibility. Random effects model was used to calculate the pooled prevalence of T. gondii infection in different animal populations which were found to harbour this infection. The critical appraisal tool for prevalence studies designed by the Joanna Briggs Institute (JBI) was used to assess the risk of bias in all included studies. Results A total of 15 studies were retrieved, reporting prevalence estimates from 4 countries in this region and in 13 animal species. Quantitative meta‐analysis estimated a pooled prevalence of 43% in felids [95% confidence interval (CI) = 23–64%, I2 index = 100%], 48% in sheep (95% CI = 27–70%, I2 = 99%) and 21% in camels (95% CI = 7–35%, I2 = 99%). Evidence of possible publication bias was found in both felids and sheep. Conclusions This meta‐analysis estimates a high prevalence of T. gondii infection in animal species which are of high economic and cultural importance to countries of this region. Hence, these findings provide valuable insight to public health authorities as well as economic and animal resources advisors in countries of the Arabian Peninsula