Dynamics of the Formation of Bright Solitary Waves of Bose-Einstein Condensates in Optical Lattices

We present a detailed description of the formation of bright solitary waves in optical lattices. To this end, we have considered a ring lattice geometry with large radius. In this case, the ring shape does not have a relevant effect in the local dynamics of the condensate, while offering a realistic set up to implement experiments with conditions usually not available with linear lattices (in particular, to study collisions). Our numerical results suggest that the condensate radiation is the relevant dissipative process in the relaxation towards a self-trapped solution. We show that the source of dissipation can be attributed to the presence of higher order dispersion terms in the effective mass approach. In addition, we demonstrate that the stability of the solitary solutions is linked with particular values of the width of the wavepacket in the reciprocal space. Our study suggests that these critical widths for stability depend on the geometry of the energy band, but are independent of the condensate parameters (momentum, atom number, etc.). Finally, the non-solitonic nature of the solitary waves is evidenced showing their instability under collisions.Comment: 7 pages, 7 figures, to appear in PR

Innovative approach for producing injectable, biodegradable materials using chitooligosaccharides and green chemistry

Although there are a number of injectable biomaterials currently under development, they present some drawbacks such as being based on synthetic polymers, needing toxic or aggressive synthesis procedures or using raw materials with low availability and/or high production costs. Having this in mind, a novel injectable biomaterial using chitooligosaccharides as starting materials was developed. This system uses a widely available and cheap polymer from marine biomass (chitosan), which can be turned into an injectable material by water-based and ecologically friendly reactions. Chitooligosaccharides were functionalized with methacrylic groups, to allow in situ crosslinking. The degree of substitution, as determined by 1H NMR, varied between 5 and 50%. The system was characterized in terms of kinetics of gel formation, rheology, degradation behavior and in vitro cytotoxicity. The gelation time could be easily tailored between 1.5 and 60 min by changing the conditions of the methacrylation reaction, and the final gel presented rheological properties typical of strong gels, that is, shear stresses in the kPa range. The cross-linked gel was degradable and nontoxic, presenting indeed an interesting cytokinetic effect. Injectable materials based on chitooligosaccharides are, therefore, an innovative system combining adequate biological performance, ease of preparation, and an ecologically friendly concept of production.The authors thank Dr. Mar Fernandez for the cytotoxicity tests. L.F.B. thanks the European Commission for supporting this work through a Marie Curie-IIF fellowship

Injectable hydrogels based on chitosan

Oligo-D-glucosamine (‘‘oligomer’’ of chitosan) seems well suited for injectable, biodegradable systems (IBS), due to their solubility in water, easier funtionalization and the possibility of working at high concentrations. Chitosan was enzymatically degraded with a commercial enzyme (Multifect Pectinase FE) at 508C and pH 5.5 during 17h, adapting a previous procedure. The oligomers were precipitated in ethanol and analysed by MALDI-TOF/MS and FTIR. They were then functionalized by reaction with methacrylic anhydride (MethA), varying ratio of amount of substance of MethA : amount of substance of -NH2 groups in the oligomer. The obtained methacrylamide- oligomers were polymerized with a potassium persulfate/ vitamin C initiation system. Both the modified oligomers and the polymerized product were analysed by FTIR and NMR. [...]info:eu-repo/semantics/publishedVersio

Preparación de mallas mediante electrohilado para la inhibición de la angiogénesis

La preparación de nanofibras por electrohilado está ganando mucho interés en la actualidad debido a su posible aplicación como sistemas de liberación controlada de fármaco. La incorporación del compuesto activo en la matriz polimérica de las fibras permite su protección frente a los procesos degradativos del organismo y su liberación controlada y localizada. Numerosas enfermedades (psoriasis, retinopatías diabéticas, crecimiento de tumores) están relacionadas con alteraciones en la angiogénesis (formación de nuevos vasos sanguíneos a partir de otros ya formados), por tanto el desarrollo de nuevos compuestos que regulen adecuadamente los procesos angiogénicos se está estudiando como una posible vía en el tratamiento de estas enfermedades. En el presente trabajo se han preparado y caracterizado nanofibras de ácido poli(D,L-láctico) cargadas con ácido 5-amino-2-naftalensulfónico o el homopolímero del ácido 2-acrilamido-2-metilpropanosulfónico, compuestos inhibidores de la acción de algunos factores de crecimiento proangiogénicos dependientes de heparina. La distinta naturaleza de los compuestos activos utilizados permitieron la obtención de diferentes perfiles de liberación, dependientes de la hidrofilia del compuesto activo, su peso molecular y la biodegradabilidad del ácido poli(D,L-láctico). Ambos sistemas mostraron una alta capacidad para inhibir la mitogénesis de fibroblastos inducida por aFGF.Preparation of nanofibers by electrospinning is gaining much attention due to their potential application as drug delivery systems. The incorporation of the active compound in the polymeric matrix of the fibers prevents degradation and allows a controlled and localized delivery of the drug. Many diseases (psoriasis, diabetic retinopathy, tumor growth) have been related to alterations in the angiogenic processes, therefore the control of angiogenesis is being investigated as a possible treatment for these diseases. In this work poly(D, L-lactic acid) nanofibers loaded with sulfonated active compounds that inhibit heparin-dependent proangiogenic growth factors (5-amino acid-2-naphthalene sulfonic acid and poly(2-acrylamido-2-methylpropane sulfonic acid) have been prepared and characterized. The different nature of the active compounds gave rise different release profiles that depended on the hydrophilic nature of the drug, molecular weight, and the biodegradation of poly (D, L-lactic acid). Both systems showed a high inhibition of fibroblasts aFGF- induced mitogenesis.Peer Reviewe

At the Crossroads. Management and Business History in Entrepreneurship Research

Recent calls for a historic turn in organization studies offer the opportunity to relaunch dialogue between management and business history research. Focusing on the specific domain of entrepreneurship research, this article illustrates the potential of mutual contributions from management and business history. In doing so, it demonstrates how historical approaches strongly influenced the early theoretical developments within entrepreneurship and demonstrates the potential to contribute to future scholarly debates. In sum, this article brings closer together business history and management studies stressing that their different perspectives and approaches are very valuable to enriching entrepreneurship research

Imaging features and safety and efficacy of endovascular stroke treatment: a meta-analysis of individual patient-level data

Peer ReviewedPostprint (author's final draft

At the crossroads. Management and business history in entrepreneurship research

Recent calls for a historic turn in organization studies offer the opportunity to relaunch dialogue between management and business history research. Focusing on the specific domain of entrepreneurship research, this article illustrates the potential of mutual contributions from management and business history. In doing so, it highlights how historical approaches strongly influenced the early theoretical developments within entrepreneurship and demonstrates the potential to contribute to future scholarly debates. In sum, this article brings closer together business history and management studies stressing that their different perspectives and approaches are very valuable to enriching entrepreneurship research

Radiovisiografía : nueva alternativa diagnóstica en odontoestomatología

Para el diagnóstico de diversas patologías odontológicas, la exploración de tejidos blandos y duros debe ser rigurosa. En muchas ocasiones, además de las técnicas de inspección, palpación, percusión y auscultación podemos servirnos de métodos complementarios como sondaje, aspiración, citología, biopsia, cultivos y para el diagnóstico por imagen nos valdremos de la radiología simple y de contraste. Actualmente podemos disponer de un nuevo método llamado Visiorradiología, que nos proporciona una serie de ventajas frente a la radiología convencional. En este trabajo se presenta un estudio comparativo entre la radiología simple y la visiorradiología en base al estudio de diversas piezas dentales, concluyéndose con los mejores resultados y posibilidades de la segunda con respecto a la primera en cuanto a rapidez, tratamiento de imágenes así como la posibilidad de almacenamiento en soporte magnético y control visual mediante impresora para el dueño de los animales.To diagnose some odontologic pathologies, the soft and tough tissues exploration must be strict. Sometimes, we can use complementary methods like sounding, aspiration, citology, biopsy, cultures and image diagnosis using ordinary and contrast radiology; in addition to the following techniques: examination, palpation, percution and auscultation. Actually we can have available a new method provide us advantages against the conventional radiology. In this study we present a comparative study between the simple radiology and the visiorradiology according to some tooth studies. We demonstrate that visiorradiology is beíter for the speed, images quality as well as the storing possibility . in magnetic supports and visual control trough the printer for the owner

Observation of spontaneous self-channelling of light in air below the collapse threshold

We report the observation of the self-guided propagation of 120 fs, 0.56 mJ infrared radiation in air for distances greater than one meter. In contrast to the known case of filamentation, in the present experiment the laser power is lower than the collapse threshold. Therefore the counter balance between Kerr self focussing and ionization induced defocussing as the stabilizing mechanism is ruled out. Instead, we find evidences of a process in which the transversal beam distribution reshapes into a form similar to a Townes soliton. We include numerical support for this conclusion