Operators Preserving K-g- Frames

K-frames were recently introduced by Găvruţa in Hilbert spaces to study atomic systems with respect to a bounded linear operator. K-g-frames are more general than of g-frames in Hilbert spaces.Results on k-g- frames have been proved through operator- theoretic results of bounded operators

Potential Impacts of Free Trade Areas and Common Currency on Sustainable Agricultural Export in Africa

Peer reviewedPublisher PD

Dysregulation of Gene Expression in the Artificial Human Trisomy Cells of Chromosome 8 Associated with Transformed Cell Phenotypes

A change in chromosome number, known as aneuploidy, is a common characteristic of cancer. Aneuploidy disrupts gene expression in human cancer cells and immortalized human epithelial cells, but not in normal human cells. However, the relationship between aneuploidy and cancer remains unclear. To study the effects of aneuploidy in normal human cells, we generated artificial cells of human primary fibroblast having three chromosome 8 (trisomy 8 cells) by using microcell-mediated chromosome transfer technique. In addition to decreased proliferation, the trisomy 8 cells lost contact inhibition and reproliferated after exhibiting senescence-like characteristics that are typical of transformed cells. Furthermore, the trisomy 8 cells exhibited chromosome instability, and the overall gene expression profile based on microarray analyses was significantly different from that of diploid human primary fibroblasts. Our data suggest that aneuploidy, even a single chromosome gain, can be introduced into normal human cells and causes, in some cases, a partial cancer phenotype due to a disruption in overall gene expression

Aneuploidy and chromosomal instability in cancer: a jackpot to chaos

Genomic instability (GIN) is a hallmark of cancer cells that facilitates the acquisition of mutations conferring aggressive or drug-resistant phenotypes during cancer evolution. Chromosomal instability (CIN) is a form of GIN that involves frequent cytogenetic changes leading to changes in chromosome copy number (aneuploidy). While both CIN and aneuploidy are common characteristics of cancer cells, their roles in tumor initiation and progression are unclear. On the one hand, CIN and aneuploidy are known to provide genetic variation to allow cells to adapt in changing environments such as nutrient fluctuations and hypoxia. Patients with constitutive aneuploidies are more susceptible to certain types of cancers, suggesting that changes in chromosome copy number could positively contribute to cancer evolution. On the other hand, chromosomal imbalances have been observed to have detrimental effects on cellular fitness and might trigger cell cycle arrest or apoptosis. Furthermore, mouse models for CIN have led to conflicting results. Taken together these findings suggest that the relationship between CIN, aneuploidy and cancer is more complex than what was previously anticipated. Here we review what is known about this complex ménage à trois, discuss recent evidence suggesting that aneuploidy, CIN and GIN together promote a vicious cycle of genome chaos. Lastly, we propose a working hypothesis to reconcile the conflicting observations regarding the role of aneuploidy and CIN in tumorigenesis

Microglial Interactions with Synapses Are Modulated by Visual Experience

Microglia, the brain's immune cells, show unique interactions with nearby synaptic elements under non-pathological conditions that are sensitive to changes in sensory experience

FTIR and ESR studies of VO2+ and MN2+ doped glasses of system 59B(2)O(3)-10As(2)O(3)-(30-x)PbO-xBaO

FTIR and the electron spin resonance studies on 59B(2)O(3)-10As(2)O(3)-(30 - x)PbO-xBaO (x = 0, 7.5, 15, 22.5, 30 mol %) glasses containing 1 mol % V2O5, or MnO2 have been carried out. The ESR spectra of V4+ ion in the glass system were recorded at X-band frequencies at 300 K. The V4+ ion in the present glass system exists as VO2+ ion in octahedral coordination with tetragonal compression. The site symmetry of vanadyl is C-4v and the ground state of 3d (1) ion is d (xy) . The spin-Hamiltonian parameters (g (aEuro-), g (aSyen) and A (aEuro-)) of VO2+ ions in the present glasses have been estimated. The spectra consist of resonance lines centered at g a parts per thousand 4.3 and g a parts per thousand 2. The resonance line centered at g a parts per thousand 4.3 has been attributed to the rhombic symmetry of the Mn2+ ions. The resonance signal at g a parts per thousand 2 is attributed to the Mn2+ ions in an environment close to an octahedral symmetry. The absence of boroxol ring in the present glass system suggested that these glasses consist of randomly connected BO3 and BO4 units. The conversion of BO3 to BO4 takes place in the glasses under investigation

Role of WO3 on DC conductivity and some optical properties of TeO2 based glasses

DC electrical conductivity and optical absorption studies have been employed to understand the influence of WO3 content on the electrical and optical properties of the TeO2-GeO2-WO3 glass system. Field emission scanning electron microscope (FESEM), Energy dispersive X-ray spectrometry (EDS) measurements have been used to confirm the glassy nature and the elemental analysis of the glass composition, respectively. DC electrical conductivity of the glasses was studied in the temperature range 423-613 K. From Arrhenius plot, the activation energies (E-act) of all the glasses have been calculated and conduction mechanism has been discussed in terms of structural changes occurred with the addition of WO3 content. The optical properties such as optical band gap (E-opt), Urbach energy (Delta E), molar refraction (R-M), metallization criterion (M), electronic polarizability of the oxide ion (alpha(o2-)) and refractive index (n) have been determined from optical absorption data and were found to be composition dependent. (c) 2012 Elsevier Ltd. All rights reserved