The polymer-based technology in the endovascular treatment of abdominal aortic aneurysms

An abdominal aortic aneurysm (AAA) is a dilatation of the abdominal aorta that progressively grows until it ruptures. Treatment is typically recommended when the diameter is more than 5 cm. The EVAR (Endovascular aneurysm repair) is a minimally invasive procedure that involves the placement of an expandable stent graft within the aorta to treat aortic disease without operating directly on the aorta. For years, stent grafts' essential design was based on metallic stent frames to support the fabric. More recently, a polymer-based technology has been proposed as an alternative method to seal AAA. This review underlines the two platforms that are based on a polymer technology: (1) the polymer-filled endobags, also known as Endovascular Aneurysm Sealing (EVAS) with Nellix stent graft; and (2) the O-ring EVAR polymer-based proximal neck sealing device, also known as an Ovation stent graft. Polymer characteristics for this particular aim, clinical applications, and durability results are hereby summarized and commented critically. The technique of inflating endobags filled with polymer to exclude the aneurysmal sac was not successful due to the lack of an adequate proximal fixation. The platform that used polymer to create a circumferential sealing of the aneurysmal neck has proven safe and effective

Water level monitoring and controlling of water treatment plants using wireless sensors in LabVIEW

Monitoring and controlling systems are taken as the main entity of any field which can ensure for the effective performance, hence its importance is rising exponentially in industry field. There can be many factors which can bring variations in those systems. This may cease the efficiency of the industry and destruction of industrial equipment. Therefore, monitoring, evaluation and controlling of the variables of any system is significantly important. The main objective of this research is to investigate the process of combining monitoring and controlling of the water level in the distribution tanks of water treatment plants by using wireless sensors network. The design and developed prototype of remote monitoring and controlling system of water levels in various tanks can be used in different parts of the water treatment plants. We have proposed, developed and tested hardware module based on two Arduino Mega2560 boards linked wirelessly by using two NRF transceivers. Remote Arduino is designed to monitor the water flow and the level of the distribution tank besides controlling the water level whenever is necessary. The real time sensors readings obtained are observed by specially designed LabVIEW application using graphical user interface running on a PC connected directly to the local Arduino. The application displays and analyses sensors reading on the front panel. Water level is controlled based on preset values entered by the user. The experimental result and percentage error curve endorse the reliability and feasibility of the proposed system to provide a solution for similar problems in industrial liquids treatment process applications

Sir epidemic and predator - prey models of fractional-order

Recently, many deterministic mathematical models such as ordinary differential equations have been extended to fractional models, which are transformed using fractional differential equations. It was believed that these fractional models are more realistic to represent the daily life phenomena. The main focus of this report is to extend the model of a predator-prey and the SIR epidemic models to fractional model. More specifically, the fractional predator-prey model which depend on the availability of a biotic resources was discussed. On the other hand, fractional SIR epidemic model with sub-optimal immunity, nonlinear incidence and saturated recovery rate was also discussed. The fractional ordinary differential equations were defined in the sense of the Caputo derivative. Stability analysis of the equilibrium points of the models for the fractional models were analyzed. Furthermore, the Hopf bifurcation analysis of each model was investigated . The result obtained showed that the model undergo Hopf bifurcation for some values. Throughout the project, the Adams-type predictor-corrector method to obtain the numerical solutions of the fractional models was applied. All computations were done by using mathematical software, Maple 18

Mechanism of action of novel NO-releasing furoxan derivatives of aspirin in human platelets

1. Incorporation of a nitric oxide (NO)-releasing moiety in aspirin can overcome its gastric side effects. 2. We investigated the NO-release patterns and antiplatelet effects of novel furoxan derivatives of aspirin (B8 and B7) in comparison to existing antiplatelet agents. 3. Cyclooxygenase (COX) activity was investigated in purified enzyme using an electron paramagnetic resonance-based technique. Concentration–response curves for antiplatelet agents±the soluble guanylate cyclase inhibitor, ODQ (50 μM) were generated in platelet-rich plasma (PRP) and washed platelets (WP) activated with collagen using turbidometric aggregometry. NO was detected using an isolated NO electrode. 4. The furoxan derivatives of aspirin (B8, B7) and their NO-free furazan equivalents (B16, B15; all 100 μM) significantly inhibited COX activity (P<0.01; n=6) in vitro and caused aspirin-independent, cGMP-dependent inhibition of collagen-induced platelet aggregation in WP. B8 was more potent than B7 (PRP IC(50)=0.62±0.1 μM for B8; 400±89 μM for B7; P<0.0001. WP IC(50)s=0.6±0.1 and 62±10 μM, respectively). The NO-free furazan counterparts were less potent antiplatelet agents (WP IC(50)s=54±3 μM and 62±10 μM, respectively; P<0.0001, B8 vs B16). Of the hybrids investigated, only B8 retained antiplatelet activity in PRP. 5. NO release from furoxan–aspirin hybrids was undetectable in buffer alone, but was accelerated in the presence of either plasma or plasma components, albumin (4%), glutathione (GSH; 3 μM) and ascorbate (50 μM), the effects of which were additive for B7 but not B8. NO generation from furoxans was greatly enhanced by platelet extract, an effect that could largely be explained by the synergistic effect of intracellular concentrations of GSH (3 mM) and ascorbate (1 mM). 6. We conclude that the decomposition of furoxan–aspirin hybrids to generate biologically active NO is catalysed by endogenous agents which may instil a potential for primarily intracellular delivery of NO. The blunting of the aspirin effects of furoxan hybrids is likely to be due to loss of the acetyl moiety in plasma; the observed antiplatelet effects are thereby primarily mediated via NO release. Compounds of this class might represent a novel means of inhibiting platelet aggregation by a combination of NO generation and COX inhibition

Spatially controlled cell adhesion on three-dimensional substrates

The microenvironment of cells in vivo is defined by spatiotemporal patterns of chemical and biophysical cues. Therefore, one important goal of tissue engineering is the generation of scaffolds with defined biofunctionalization in order to control processes like cell adhesion and differentiation. Mimicking extrinsic factors like integrin ligands presented by the extracellular matrix is one of the key elements to study cellular adhesion on biocompatible scaffolds. By using special thermoformable polymer films with anchored biomolecules micro structured scaffolds, e.g. curved and µ-patterned substrates, can be fabricated. Here, we present a novel strategy for the fabrication of µ-patterned scaffolds based on the “Substrate Modification and Replication by Thermoforming” (SMART) technology: The surface of a poly lactic acid membrane, having a low forming temperature of 60°C and being initially very cell attractive, was coated with a photopatterned layer of poly(L-lysine) (PLL) and hyaluronic acid (VAHyal) to gain spatial control over cell adhesion. Subsequently, this modified polymer membrane was thermoformed to create an array of spherical microcavities with diameters of 300 µm for 3D cell culture. Human hepatoma cells (HepG2) and mouse fibroblasts (L929) were used to demonstrate guided cell adhesion. HepG2 cells adhered and aggregated exclusively within these cavities without attaching to the passivated surfaces between the cavities. Also L929 cells adhering very strongly on the pristine substrate polymer were effectively patterned by the cell repellent properties of the hyaluronic acid based hydrogel. This is the first time cell adhesion was controlled by patterned functionalization of a polymeric substrate with UV curable PLL-VAHyal in thermoformed 3D microstructures

A Synthesis of the Literature on the Relationship Between Food Access and Overweight and Obesity in African American Adolescents

Food access shapes a community’s nutritional environment and impacts the health and physical well-being of its residents. When a community does not have adequate access to outlets that offer healthy options, it is difficult to maintain a healthy diet. As a result, we often see higher rates of chronic disease, overweight and obesity among some populations. African American communities may be disproportionately affected by overweight and obesity because of limited food access. This literature review examines the public health significance of food access and how the presence of full service grocery stores impacts eating habits and overweight and obesity among African American adolescents. The results are primarily cross-sectional studies organized and presented in three sections: (1) food environment, (2) eating habits, and (3) policy implications. The findings in this literature review suggest that the problem of overweight and obesity in African American adolescents is indeed a multi-faceted issue. While there does appear to be a correlation between access to full service supermarkets and eating behaviors, overweight and obesity, there are other factors to consider. It is unclear if the presence of more full-service supermarkets alone is enough to significantly impact a reduction of overweight and obesity among African-American youth. While quantitative studies provide important baseline data, researchers should consider developing qualitative studies that may offer additional insight into individual, family and environmental factors that vary geographically

Reti sociali per le politiche pubbliche tra processi di vittimizzazione e dimensioni della sicurezza comunitaria

La riscoperta del carattere “comunitario” della società secondo la chiave di lettura della prevenzione (di comunità) rivela una persistente antitesi tra social support e controllo sociale. L’accoglimento di questa tesi presuppone un atteggiamento consapevolmente critico nei confronti del preteso “fallimento” del welfare state, identificato come la principale conseguenza dell’assegnazione alle politiche di welfare dell’obiettivo della riduzione della criminalità. In tal modo si dimostra la vaghezza della (presunta) corrispondenza tra prevenzione situazionale – esaminata anche alla luce della logica situazionale riferita all’analisi della situazione in cui l’agente intraprende l’azione – e valori conservatori, quali l’incisivo ridimensionamento della sfera pubblica e la promozione dell’etica della responsabilità individuale, e risultano radicalmente differenziati gli approcci orientati alla riduzione della criminalità e quelli indirizzati al miglioramento del welfare sociale, benché, come dimostra il modello nordico del welfare state, quest’ultimo risulti compatibile con la prevenzione situazionale della criminalità. In questo scenario le azioni di sviluppo della comunità sono finalizzate al miglioramento complessivo delle condizioni sociali, abitative e dei servizi dando in tal modo attuazione agli obiettivi di rivitalizzare il territorio, favorire l’attività sociale ed evitare il degrado di situazioni critiche. Ci si propone inoltre di indagare i legami sociali su base locale che valgono come risorse del controllo sociale informale, o controllo sociale di comunità e di affrontare la possibile ed auspicata integrazione tra il paradigma del social support e l’analisi della devianza e del controllo sociale. In questo quadro appare opportuno connettere, ed esaminare congiuntamente, i concetti (e gli strumenti) delle «reti sociali» e del «social support» con la nozione, oggi estremamente diffusa nelle scienze sociali, di «capitale sociale». Al riguardo la tesi predominante, elaborata da Robert Putnam, prospetta una relazione inversa tra capitale sociale e criminalità: l’incremento dei livelli di capitale sociale produrrebbe una sensibile riduzione dei livelli di criminalità nella misura in cui tale fenomeno appare come la principale conseguenza del degrado sociale, per cui una sua elevata incidenza può fungere da indicatore della destabilizzazione della struttura sociale di una comunità. Alle posizioni che, almeno nel breve periodo, evidenziano con diverse sfumature una relazione inversamente proporzionale tra capitale sociale e criminalità si affiancano tuttavia tesi che qui saranno discusse che sostengono l’esistenza di una più elevata esposizione al rischio di vittimizzazione nelle aree in cui si registra una più significativa incidenza del capitale sociale

Matter density perturbations in interacting quintessence models

Models with dark energy decaying into dark matter have been proposed to solve the coincidence problem in cosmology. We study the effect of such coupling in the matter power spectrum. Due to the interaction, the growth of matter density perturbations during the radiation dominated regime is slower compared to non-interacting models with the same ratio of dark matter to dark energy today. This effect introduces a damping on the power spectrum at small scales proportional to the strength of the interaction and similar to the effect generated by ultrarelativistic neutrinos. The interaction also shifts matter--radiation equality to larger scales. We compare the matter power spectrum of interacting quintessence models with the measurments of 2dFGRS. We particularize our study to models that during radiation domination have a constant dark matter to dark energy ratio.Comment: 11 pages, 4 figures, accepted for publication in Phys. Rev.

Perceptions of Present and Future Climate Change Impacts on Water Availability for Agricultural Systems in the Western Mediterranean Region

Many Mediterranean countries have experienced water shortages during the last 20 years and future climate change projections foresee further pressure on water resources. This will have significant implications for irrigation water management in agricultural systems in the future. Through qualitative and quantitative empirical research methods carried out on a case study on four Mediterranean farming systems located in Oristano, Italy, we sought to understand the relationship between farmers' perceptions of climate change (i.e., increased temperature and decreased precipitation) and of present and future water availability for agriculture as forecasted by climatic and crop models. We also explored asymmetries between farmers' perceptions and present and future climate change and water scenarios as well as factors influencing perceptions. Our hypotheses were that farmers' perceptions are the main drivers of actual water management practices and that sustainable practices can emerge from learning spaces designed from the understanding of the gaps between perceptions and scientific evidences. Results showed that most farmers perceived that climate change is occurring or will occur in their area. They also perceived that there has been an increased temperature trend, but also increased precipitation. Therefore, they are convinced that they have and will have enough irrigation water for agriculture in the near future, while climate change projections foresee an increasing pressure on water resources in the Mediterranean region. Such results suggest the need for (i) irrigation management policies that take into account farmers' perceptions in order to promote virtuous behaviors and improve irrigation water use efficiency; (ii) new, well-designed learning spaces to improve the understanding on climate change expectations in the near future in order to support effective adaptive responses at the farm and catchment scales

CMB Anisotropies in the Presence of Extra Dimensions

We discuss the effect of the time evolution of extra dimensions on CMB anisotropies and large-scale structure formation. We study the impact of scalar fields in a low-energy effective description of a general class of brane world models on the temperature anisotropy power spectrum. We show that when the coupling between these scalar fields and matter evolves over cosmological timescales, current observations of the CMB anisotropies can constrain primordial values of the fields in a manner complementary to local, late-time tests of gravity. We also present the effect of these fields on the polarization anisotropy spectra and the growth of large-scale structure, showing that future CMB observations will constrain theories of the Universe involving extra dimensions even further.Comment: 17 pages, 15 figure