Homogenization Model for Aberrant Crypt Foci

Several explanations can be found in the literature about the origin of colorectal cancer. There is however some agreement on the fact that the carcinogenic process is a result of several genetic mutations of normal cells. The colon epithelium is characterized by millions of invaginations, very small cavities, called crypts, where most of the cellular activity occurs. It is consensual in the medical community, that a potential first manifestation of the carcinogenic process, observed in conventional colonoscopy images, is the appearance of Aberrant Crypt Foci (ACF). These are clusters of abnormal crypts, morphologically characterized by an atypical behavior of the cells that populate the crypts. In this work an homogenization model is proposed, for representing the cellular dynamics in the colon epithelium. The goal is to simulate and predict, in silico, the spread and evolution of ACF, as it can be observed in colonoscopy images. By assuming that the colon is an heterogeneous media, exhibiting a periodic distribution of crypts, we start this work by describing a periodic model, that represents the ACF cell-dynamics in a two-dimensional setting. Then, homogenization techniques are applied to this periodic model, to find a simpler model, whose solution symbolizes the averaged behavior of ACF at the tissue level. Some theoretical results concerning the existence of solution of the homogenized model are proven, applying a fixed point theorem. Numerical results showing the convergence of the periodic model to the homogenized model are presented.Comment: 26 pages, 4 figure

The Bulletin, series 40, number 2, July (1944)

The state of the collegehttps://red.mnstate.edu/thebulletin/1073/thumbnail.jp

Production procedures and mechanical behaviour of interlocking stabilized compressed earth blocks (ISCEBs) manufactured using float ram 1.0 press

This paper illustrates an innovative manufacturing procedure for producing handcrafted interlocking stabilized compressed earth blocks (ISCEBs). A comparison of the mechanical properties of ISCEBs is conducted to assess the influence of varying components. The ISCEBs are manufactured by employing different block densities with three distinct mixtures (earth, earth and lime, earth and straw) and by using a human-powered machine named Float RAM 1.0 Press. The manual press was conceived for regions with limited access to technology and allows the production of interlocking blocks via two modes of compaction: mono-directional and bi-directional. A production average of approximately 30 blocks/hour corresponding to the work of three people is achieved. Three-point bending tests and uniaxial compression tests are carried out to investigate the ISCEB mechanical behaviour. The improvements obtained by incorporating additives into the subset of ISCEBs made from a pure earth mixture are tested. The aim of this work is to identify, for this specific technology, the relationship between production parameters and the consequent behaviour of different stabilization methods. A correlation is found between the compaction force and the compression strength of ISCEBs. The addition of lime increases strength and causes the blocks to exhibit a brittle behaviour. Moreover, the incorporation of straw fibres improves the tensile strength and ductility without significantly affecting the compression strength of the blocks. Energy-based parameters are obtained for all the tests, allowing the assessment of the ISCEB mechanical and dissipation properties

A polymer supported palladium(II) \u3b2-ketoesterate complex as active and recyclable pre-catalyst for selective reduction of quinolines in water with sodium borohydride

A polymer supported palladium catalyst, obtained by copolymerization of Pd(AAEMA)2 [AAEMA- = deprotonated form of 2-(acetoacetoxy) ethyl methacrylate] with ethyl methacrylate (co-monomer) and ethylene glycol dimethacrylate (cross-linker), exhibited excellent activity and selectivity for the hydrogenation of quinolines to 1,2,3,4-tetrahydroquinolines in the presence of NaBH4 as hydrogen donor in water. Both the activity and selectivity could be maintained for at least seven reaction runs. No metal leaching into solution occurred during recycles. TEM analyzes carried out on the catalyst showed that the active species were supported palladium nanoparticles having a mean size of 3 nm, which did not aggregate with the recycles

Synthesis of NH-sulfoximines from sulfides by chemoselective one-pot N- and O-transfers

Direct synthesis of NH-sulfoximines from sulfides has been achieved through O and NH transfer in the same reaction, occurring with complete selectivity. The reaction is mediated by bisacetoxyiodobenzene under simple conditions and employs inexpensive N-sources. Preliminary studies indicate that NH-transfer is likely to be first, followed by oxidation, but the reaction proceeds successfully in either order. A wide range of functional groups and biologically relevant compounds are tolerated. The use of AcO15NH4 affords 15N-labeled compounds

Catalytic activities of heterogeneous catalysts obtained by copolymerization of metal-containing 2-(acetoacetoxy)ethyl methacrylate

AbstractAmong the synthetic strategies commonly used for supporting a metal complex onto an organic polymer in order to obtain an heterogenous catalyst, a valid choice is to synthesize a metal containing monomer (MCM), which can subsequently be subjected to polymerization with suitable comonomers and crosslinkers, achieving a supported transition metal catalyst as a metal-containing polymer (MCP). In this context, during the last two decades, we explored the use of 2-(acetoacetoxy)ethyl methacrylate (HAAEMA) as a ligand to prepare several MCMs for the relevant MCPs. In this review we summarize and discuss our developments in the studies of the catalytic activity of these "hybrid" catalysts. These catalysts have demonstrated high efficiency and/or excellent selectivity in several kinds of chemical reactions and very often they could be recovered and reused in multiple cycles maintaining their activity and selectivity without suffering from appreciable metal leaching

The effects of physical training without equipment on pain perception and balance in the elderly: a randomized controlled trials

Background: Research supports a link between exercise and falls prevention in the older population. Objectives: Our aims were to evaluate pain perception and balance skills in a group of elderly subjects and to examine the consequences of a standardized equipment-free exercise program intervention on these variables. The study utilized a randomized controlled trial method. Methods: 92 subjects were recruited from a rural Sicilian village (Resuttano, Sicily, Italy). Subjects were randomly split into two groups, an experimental group (EG; n= 49) and a control group (CG; n =43). Qualified fitness instructors delivered the standardized physical exercise program for the EG whilst the CG did not receive this exercise intervention. The Berg Balance Scale and the Oswestry Disability Index were administered in both groups before (T0) and after the intervention (T1). Results: At T1, the EG group significantly improvement in balance (p<0.0001) and pain perception (p<0.0001). No significant differences were found within the CG both in BBS and ODI, respectively. Conclusions: Our findings suggest that a 13-weeks standardized exercise equipment-free program is effective in improving balance and perception of pain in the elderly. This type of intervention can consequently provide a low cost strategy to counteract the rate of disability in elderly

Numerical solution of general Bordered ABD linear systems by cyclic reduction,

In this paper we analyze the solution of Borderd Almost Block Diagonal (BABD) linear systems arising from the discretization of BVPs with nonseparated boundary conditions using some well known numerical methods, for example spline collocation at Gaussian points. Several approaches based on cyclic reduction are proposed and compared