Idempotents in symmetric semigroups

AbstractWe count the number of idempotent elements in a certain section of the s symmetric semigroup Sn on n letters. As a corollary of our result we have that every maximal principal right ideal of Sn contains ∑i=1n−1in−i−1(n−2i−1)+(n−1i) idempotent elements. Let Tr (1 ⩽ r ⩽ n − 1) be the set of all elements of Sn of rank less than or equal to r, and let Dr denote the set of all elements of Sn of rank r. Then Tr is a semigroup generated by the idempotent elements of Dr. We shall obtain a maximal mutant of Tn−1 = SnDn

Rational choice function derived from a fuzzy preference

We shall prove that every fuzzy rational choice function is fuzzy regular (see Richter [6, p. 36] ), count the total number of the fuzzy rational choice ftmctions on a set of four elements and consider a semigroup of all fuzzy rational choice functions on a set

Systematic Determination of Absolute Absorption Cross-section of Individual Carbon Nanotubes

Determination of optical absorption cross-section is always among the central importance of understanding a material. However its realization on individual nanostructures, such as carbon nanotubes, is experimentally challenging due to the small extinction signal using conventional transmission measurements. Here we develop a technique based on polarization manipulation to enhance the sensitivity of single-nanotube absorption spectroscopy by two-orders of magnitude. We systematically determine absorption cross-section over broad spectral range at single-tube level for more than 50 chirality-defined single-walled nanotubes. Our data reveals chirality-dependent one-dimensional photo-physics through the behaviours of exciton oscillator strength and lifetime. We also establish an empirical formula to predict absorption spectrum of any nanotube, which provides the foundation to determine quantum efficiencies in important photoluminescence and photovoltaic processes

The Enhanced Pneumococcal LAMP Assay: A Clinical Tool for the Diagnosis of Meningitis due to \u3cem\u3eStreptococcus pneumoniae\u3c/em\u3e

Background: Streptococcus pneumoniae is a leading cause of invasive bacterial disease in developed and developing countries. We studied the loop-mediated isothermal amplification (LAMP) technique to assess its suitability for detecting S. pneumoniae nucleic acid in cerebrospinal fluid (CSF). Methodology/Principal Findings: We established an improved LAMP assay targeting the lytA gene (Streptococcus pneumoniae [Sp] LAMP). The analytical specificity of the primers was validated by using 32 reference strains (10 Streptococcus and seven non-Streptococcus species) plus 25 clinical alpha-hemolytic streptococcal strains, including four S. pneumoniae strains and 21 other strains (3 S. oralis, 17 S. mitis, and one Streptococcus species) harboring virulence factorencoding genes (lytA or ply). Within 30 minutes, the assay could detect as few as 10 copies of both purified DNA and spiked CSF specimens with greater sensitivity than conventional polymerase chain reaction (PCR). The linear determination range for this assay is 10 to 1,000,000 microorganisms per reaction mixture using real-time turbidimetry. We evaluated the clinical sensitivity and specificity of the Sp LAMP assay using 106 randomly selected CSF specimens from children with suspected meningitis in Korea, China and Vietnam. For comparison, CSF specimens were also tested against conventional PCR and culture tests. The detection rate of the LAMP method was substantially higher than the rates of PCR and culture tests. In this small sample, relative to the LAMP assay, the clinical sensitivity of PCR and culture tests was 54.5% and 33.3%, respectively, while clinical specificity of the two tests was 100%. Conclusions/Significance: Compared to PCR, Sp LAMP detected S. pneumoniae with higher analytical and clinical sensitivity. This specific and sensitive LAMP method offers significant advantages for screening patients on a population basis and for diagnosis in clinical settings

SIRT1-mediated downregulation of p27(Kip1) is essential for overcoming contact inhibition of Kaposi's sarcoma-associated herpesvirus transformed cells

Kaposi's sarcoma-associated herpesvirus (KSHV) is an oncogenic virus associated with Kaposi's sarcoma (KS), a malignancy commonly found in AIDS patients. Despite intensive studies in the last two decades, the mechanism of KSHV-induced cellular transformation and tumorigenesis remains unclear. In this study, we found that the expression of SIRT1, a metabolic sensor, was upregulated in a variety of KSHV-infected cells. In a model of KSHV-induced cellular transformation, SIRT1 knockdown with shRNAs or knockout by CRISPR/Cas9 gene editing dramatically suppressed cell proliferation and colony formation in soft agar of KSHV-transformed cells by inducing cell cycle arrest and contact inhibition. SIRT1 knockdown or knockout induced the expression of cyclin-dependent kinase inhibitor 1B (p27(Kip1)). Consequently, p27 knockdown rescued the inhibitory effect of SIRT1 knockdown or knockout on cell proliferation and colony formation. Furthermore, treatment of KSHV-transformed cells with a SIRT1 inhibitor, nicotinamide (NAM), had the same effect as SIRT1 knockdown and knockout. NAM significantly inhibited cell proliferation in culture and colony formation in soft agar, and induced cell cycle arrest. Significantly, NAM inhibited the progression of tumors and extended the survival of mice in a KSHV-induced tumor model. Collectively, these results demonstrate that SIRT1 suppression of p27 is required for KSHV-induced tumorigenesis and identify a potential therapeutic target for KS.

Utilization of a magnetic field-driven microscopic motion for piezoelectric energy harvesting.

In spite of the recent advances in the development of high performing piezoelectric materials, their applications are typically limited to the direct conversion of mechanical impact energy to electrical energy, potentially risking mechanical failures. In this study, we developed piezoelectric poly(vinylidenefluoride-trifluoroethylene) (P(VDF-TrFE)) nanofibers integrated with SiO2-shelled Fe3O4 magnetic nanoparticles, to utilize magnetic energy to reliably drive the piezoelectric effect. Specifically, we show that the shape of the magnetic nanoparticles exerts a significant effect on the efficiency of the magneto-mechano-electrical energy conversion as magnetic nanorods exhibit approximately 70% enhancement in electric field generation under cyclic magnetic fields as compared to nanospheres. Under an alternating magnetic field of 200 mT, the magnetic nanorod-piezoelectric nanofiber composite generated a peak-to-peak voltage of approximately 30 mVp-p with a superior durability without any performance degradation after over 1 million cycles. This study demonstrates the potential of magnetic-field responsive, piezoelectric-based materials in energy harvesting applications from non-mechanical energy sources

Polymorphism of a COLIA1 Gene Sp1 Binding Site in Korean Women with Pelvic Organ Prolapse

PURPOSE: To evaluate the possible influence of G-->T substitution at the Sp1-binding site of the COLIA1 gene on the risk of pelvic organ prolapse (POP). MATERIALS AND METHODS: The study group consisted of 15 women with advanced stage POP. Fifteen control subjects with uterine myomas among the postmenopausal women were matched for age and parity. DNA was obtained from peripheral blood leukocytes. The fragments of the first intron of the COLIA1 gene were amplified by real time polymerase chain reaction. The polymorphism was identified using LightCycler Technology with hybridization probes. Sequencing reactions were performed on each template using commercial primer. RESULTS: Two groups had no significant difference in medical history, surgical, and smoking history. The homozygous peaks in two groups were noted at 57 on melting curve analysis. Sequencing reactions confirmed the G/G alleles in the 30 specimens tested. We could not find any polymorphism at the Sp1-binding site in COLIA1 gene with advanced stage POP. Statistical significance was considered to be p < .05. CONCLUSION: The polymorphism of the Sp1-binding site in the COLIA1 gene did not contribute to the development of POP in Korea.ope