6,989 research outputs found
On behavior of the fifth algebraic transfer
In this paper, we show that Singer's fifth transfer is not an epimorphism in
degree 11. More precisely, it does not detect the element P(h_2) in
Ext_A^{5,16}(F_2,F_2).Comment: This is the version published by Geometry & Topology Monographs on 14
November 200
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The RNA Polymerase II Core Promoter in Drosophila.
Transcription by RNA polymerase II initiates at the core promoter, which is sometimes referred to as the "gateway to transcription." Here, we describe the properties of the RNA polymerase II core promoter in Drosophila The core promoter is at a strategic position in the expression of genes, as it is the site of convergence of the signals that lead to transcriptional activation. Importantly, core promoters are diverse in terms of their structure and function. They are composed of various combinations of sequence motifs such as the TATA box, initiator (Inr), and downstream core promoter element (DPE). Different types of core promoters are transcribed via distinct mechanisms. Moreover, some transcriptional enhancers exhibit specificity for particular types of core promoters. These findings indicate that the core promoter is a central component of the transcriptional apparatus that regulates gene expression
Evolution of structure of SiO2 nanoparticles upon cooling from the melt
Evolution of structure of spherical SiO2 nanoparticles upon cooling from the
melt has been investigated via molecular-dynamics (MD) simulations under
non-periodic boundary conditions (NPBC). We use the pair interatomic potentials
which have weak Coulomb interaction and Morse type short-range interaction. The
change in structure of SiO2 nanoparticles upon cooling process has been studied
through the partial radial distribution functions (PRDFs), coordination number
and bond-angle distributions at different temperatures. The core and surface
structures of nanoparticles have been studied in details. Our results show
significant temperature dependence of structure of nanoparticles. Moreover,
temperature dependence of concentration of structural defects in nanoparticles
upon cooling from the melt toward glassy state has been found and discussed.Comment: 12 pages, 6 figure
Targeted antiangiogenic agents in combination with cytotoxic chemotherapy in preclinical and clinical studies in sarcoma.
Sarcomas are a heterogeneous group of mesenchymal malignancies. In recent years, studies have demonstrated that inhibition of angiogenic pathways or disruption of established vasculature can attenuate the growth of sarcomas. However, when used as monotherapy in the clinical setting, these targeted antiangiogenic agents have only provided modest survival benefits in some sarcoma subtypes, and have not been efficacious in others. Preclinical and early clinical data suggest that the addition of conventional chemotherapy to antiangiogenic agents may lead to more effective therapies for patients with these tumors. In the current review, the authors summarize the available evidence and possible mechanisms supporting this approach
To eat or not to eat: Urbanization and the foraging behaviors of Michigan passerines
Urbanization creates novel problems for wildlife, potentially altering the foraging behavior of passerine birds. Foraging is driven by factors like food preference and food accessibility; the foraging of urban birds may be more innovative due to frequent exposure to unfamiliar items. I hypothesized that high novelty exposure in urban birds would promote faster discovery and longer visits to novel feeders compared to rural conspecifics. Additionally, I hypothesized that birds would prioritize food quality over access regardless of habitat, but when faced with barriers, urban birds would be better at accessing food compared to rural birds because of frequent exposure to novel obstacles. Recording bird visitations to paired bird feeders of differing food quality, I found that feeder discovery was not significantly different between the seed types or habitats. Rural birds spent half as much time at low access feeders compared to urban birds; when feeders were caged, rural birds discovered both seed types more quickly than the urban counterparts. Additionally, higher-quality food had greater consumption in both environments regardless of accessibility, although rural birds removed more low-quality food than urban birds when the more nutritional option was obstructed. This study reveals the importance of food preferences in driving avian feeding behaviors and how bird communities may be shaped by the food quality and degree of fragmentation of the habitat
Feasibility of Integrating Tripterygium wilfordii into Modern Cancer Therapy for Increased Efficacy and Minimal Toxicity
Cancer is the second leading cause of death in the U.S. and millions of novel cancer cases are being diagnosed each year. While chemotherapy and ionizing radiation are effective treatments against these malignant tumors, the adverse effects that accompany such treatments are devastating. In order to find alternative treatment methods with less side effects, we turn to Eastern herbal medicine. Recent scientific research has found that Tripterygium wilfordii, an herbal medicine traditionally used to treat inflammation in China, contains compounds (triptolide and celastrol) that prevent the growth of solid tumors, induce apoptosis, and prevent metastasis of developed tumors. Investigations on these compounds on various cancer cells lines (in vitro and in vivo) have revealed insight into their mechanism, mode of action, and toxicity. In order to circumvent the potentially fatal side effects of triptolide and celastrol, it was proposed that roots of T. wilfordii, from which the compounds are extracted, be used as a treatment for cancer. Methods for testing the efficacy and toxicity of the roots on the different cell lines previously studied are outlined in this paper. If the results from the proposed experiment conflict with expectation, then future studies on combination drugs using triptolide and celastrol with other non-bioactive compounds within the roots should be done to develop new anti-cancer drugs with low toxicity.https://scholarscompass.vcu.edu/uresposters/1165/thumbnail.jp
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