Phase diagram for a single flexible Stockmayer polymer at zero field

The equilibrium conformations of a flexible permanent magnetic chain that consists of a sequence of linked magnetic colloidal nanoparticles with short-ranged Lennard-Jones attractive interactions (Stockmayer polymer) are thoroughly analysed via Langevin dynamics simulations. A tentative phase diagram is presented for a chain of length $N=100$. The phase diagram exhibits several unusual conformational phases when compared with the non-magnetic chains. These phases are characterised by a large degree of conformational anisotropy, and consist of closed chains, helicoidal-like states, partially collapsed states, and very compact disordered states. The phase diagram contains several interesting features like the existence of at least two 'triple points'

Interpolation of families

We identify the intermédiate space of a complex interpolation family - in the sense of Coifman, Cwikel, Rochberg, Sagher and Weissof LP spaces with change of measure, for the complex interpolation method associated to an analytic functional

Kinetics of phase transformation in depletion driven colloids

PACS number(s): 82.70.Gg, 82.70.RrWe present results from a detailed numerical study of the kinetics of phase transformations in a model two-dimensional depletion-driven colloidal system. Transition from a single, dispersed phase to a two-phase coexistence of monomers and clusters is obtained as the depth of the interaction potential among the colloidal particles is changed. Increasing the well depth further, fractal clusters are observed in the simulation. These fractal clusters have a hybrid structure in the sense that they show hexagonal closed-packed crystalline ordering at short length scales and a ramified fractal nature at larger length scales. For sufficiently deep potential wells, the diffusion-limited cluster-cluster aggregation model is recovered in terms of the large-scale fractal dimension Df of the clusters, the kinetic exponent z, and the scaling form of the cluster size distribution. For shallower well depths inside the two-phase coexistence region, simulation results for the kinetics of cluster growth are compared with intermediate-stage phase separation in binary mixtures. In the single-phase region, growth kinetics agree well with a mean-field aggregation-fragmentation model of Sorensen, Zhang, and Taylor.J.J.C. and T.S. acknowledge financial support from the Spanish MCyT through Grant No. BMF2001-0341-C02-01. A.C. and C.S.were supported by NASA through Grant No. NAG 3-2360Peer reviewe

New insights into molecular pathways associated with flatfish ovarian development and atresia revealed by transcriptional analysis

<p>Abstract</p> <p>Background</p> <p>The Senegalese sole (<it>Solea senegalensis</it>) is a marine flatfish of increasing commercial interest. However, the reproduction of this species in captivity is not yet controlled mainly because of the poor knowledge on its reproductive physiology, as it occurs for other non-salmonid marine teleosts that exhibit group-synchronous ovarian follicle development. In order to investigate intra-ovarian molecular mechanisms in Senegalese sole, the aim of the present study was to identify differentially expressed genes in the ovary during oocyte growth (vitellogenesis), maturation and ovarian follicle atresia using a recently developed oligonucleotide microarray.</p> <p>Results</p> <p>Microarray analysis led to the identification of 118 differentially expressed transcripts, of which 20 and 8 were monitored by real-time PCR and in situ hybridization, respectively. During vitellogenesis, many up-regulated ovarian transcripts had putative mitochondrial function/location suggesting high energy production (NADH dehydrogenase subunits, cytochromes) and increased antioxidant protection (selenoprotein W2a), whereas other regulated transcripts were related to cytoskeleton and zona radiata organization (zona glycoprotein 3, alpha and beta actin, keratin 8), intracellular signalling pathways (heat shock protein 90, Ras homolog member G), cell-to-cell and cell-to-matrix interactions (beta 1 integrin, thrombospondin 4b), and the maternal RNA pool (transducer of ERBB2 1a, neurexin 1a). Transcripts up-regulated in the ovary during oocyte maturation included ion transporters (Na⁺-K⁺-ATPase subunits), probably required for oocyte hydration, as well as a proteinase inhibitor (alpha-2-macroglobulin) and a vesicle calcium sensor protein (extended synaptotagmin-2-A). During follicular atresia, few transcripts were found to be up-regulated, but remarkably most of them were localized in follicular cells of atretic follicles, and they had inferred roles in lipid transport (apolipoprotein C-I), chemotaxis (leukocyte cell-derived chemotaxin 2,), angiogenesis (thrombospondin), and prevention of apoptosis (S100a10 calcium binding protein).</p> <p>Conclusion</p> <p>This study has identified a number of differentially expressed genes in the ovary that were not previously found to be regulated during ovarian development in marine fish. Specifically, we found evidence, for the first time in teleosts, of the activation of chemoattractant, angiogenic and antiapoptotic pathways in hypertrophied follicular cells at the onset of ovarian atresia.</p

La relación médico-paciente en el tratamiento de la diabetes tipo 1. Un estudio cualitativo

ObjetivosConocer las experiencias y las expectativas de pacientes con diabetes tipo 1 (DM1) y sus familiares sobre la relación que establecen con sus médicos y su influencia en la forma de afrontar la enfermedad y el tratamiento.DiseñoDiseño cualitativo a través de grupos focales realizado en 2001.EmplazamientoDistintos centros sanitarios de Granada y Sevilla.ParticipantesPacientes con DM1, familiars y/o cuidadores.MétodoMuestreo teórico con representación de los perfiles más característicos. Procedimiento de análisis cualitativo: asignación de códigos al texto, triangulación e interpretación de resultados.ResultadosLa relación médico-paciente influye decisivamente en la vivencia emocional de la enfermedad y en la manera en que los pacientes asumen el control. Los pacientes entrevistados aseguran que la relación con sus médicos está centrada en los signos y los síntomas de la enfermedad, y que el aspecto emocional se deja de lado. Es frecuente que los profesionales basen su comunicación en la reprimenda y en la amenaza. Los tratamientos se imponen más que se consensúan, y las posibilidades de participación en las decisiones clínicas son escasas. En consecuencia, los pacientes desarrollan estrategias para tomar sus propias decisiones sobre el tratamiento adaptándolo a su vida.ConclusionesDesean un modelo de relación con sus médicos en el que les escuchen, empaticen con su situación, comprendan los problemas que enfrentan para seguir el tratamiento, les transmitan ánimos y adapten sus recomendaciones a las circunstancias vitales y emocionales de cada paciente. Se prefiere a los profesionales que combinan la competencia técnica (incluida la dimensión relacional) con la humanidad y la amabilidad, y que asumen su corresponsabilidad en el éxito del tratamiento.ObjectivesTo know the experiences and expectations of diabetes mellitus type 1 (DM1) patients and their relatives as regards the relationships established with doctors, and the impact of such relationships on their strategies to cope with the disease and treatment.DesignQualitative design based on focus groups conducted in 2001.LocationSeveral health care centres in Granada and Seville, Spain.ParticipantsDM1 patients and their relatives and/or carers.MethodTheory-based sampling including the most representative profiles. Qualitative analysis procedure: text coding, triangulation and interpretation of results.ResultsDoctor/patient relationship highly influences the emotional experience of disease and the way patients gain control over it. Interviewed patients said that the relationship with doctors is focused on disease signs and symptoms, leaving emotional aspects aside. Very often, provider communication is built on recrimination and threat. Treatment is imposed rather than agreed, with scarce opportunities for participating in clinical decisions. Patients develop strategies to take their own decisions and adapting treatment to their daily life.ConclusionsPatients value a relationship model whereby providers listen and empathise with their situation, understand their difficulties in treatment compliance, encourage them, and adapt recommendations to the personal and emotional circumstances of each patient. They prefer doctors combining professional competence-including relational skills-with humanity and kindness, as well as being capable of assuming their co-responsibility in treatment success

Supramolecular Magnetic Brushes: The Impact of Dipolar Interactions on the Equilibrium Structure

The equilibrium structure of supramolecular magnetic filament brushes is analyzed at two different scales. First, we study the density and height distributions for brushes with various grafting densities and chain lengths. We use Langevin dynamics simulations with a bead-spring model that takes into account the cross-links between the surface of the ferromagnetic particles, whose magnetization is characterized by a point dipole. Magnetic filament brushes are shown to be more compact near the substrate than nonmagnetic ones, with a bimodal height distribution for large grafting densities. This latter feature makes them also different from brushes with electric dipoles. Next, in order to explain the observed behavior at the filament scale, we introduce a graph theory analysis to elucidate for the first time the structure of the brush at the scale of individual beads. It turns out that, in contrast to nonmagnetic brushes, in which the internal structure is determined by random density fluctuations, magnetic forces introduce a certain order in the system. Because of their highly directional nature, magnetic dipolar interactions prevent some of the random connections to be formed. On the other hand, they favor a higher connectivity of the chains' free and grafted ends. We show that this complex dipolar brush microstructure has a strong impact on the magnetic response of the brush, as any weak applied field has to compete with the dipole-dipole interactions within the crowded environment.This research has been partially supported by the Austrian Research Fund (FWF): START-Projekt Y 627-N27. The authors are grateful to the Ural Federal University stimulating programme. S.S.K, E.S.P., and E.V.N. are supported by RFBR mol-a-ved 15-32-20549. The work of E.V.N. was partially supported by the President of RF, Grant NO MK-5216.2015.2. S.S.K. is supported by the Ministry of Education and Science of the Russian Federation (Contract 02.A03.21.000, Project 3.12.2014/K) and EU-Project 642774 ETN-Colldense. P.A.S. acknowledges financial support from the Universitat de les Illes Balears within its Programa de foment de la recerca. T.S. and J.J.C. were supported by the project FIS2012-30634 (funded by the Spanish Mineco). J.J.C. and T.S. also acknowledge funding from a grant awarded by the Conselleria d’Educació, Cultura i Universitats del Govern de les Illes Balears and the European Social Fund (ESF).Peer Reviewe

Relationship of Weather Types on the Seasonal and Spatial Variability of Rainfall, Runoff, and Sediment Yield in the Western Mediterranean Basin

Rainfall is the key factor to understand soil erosion processes, mechanisms, and rates. Most research was conducted to determine rainfall characteristics and their relationship with soil erosion (erosivity) but there is little information about how atmospheric patterns control soil losses, and this is important to enable sustainable environmental planning and risk prevention. We investigated the temporal and spatial variability of the relationships of rainfall, runoff, and sediment yield with atmospheric patterns (weather types, WTs) in the western Mediterranean basin. For this purpose, we analyzed a large database of rainfall events collected between 1985 and 2015 in 46 experimental plots and catchments with the aim to: (i) evaluate seasonal differences in the contribution of rainfall, runoff, and sediment yield produced by the WTs; and (ii) to analyze the seasonal efficiency of the different WTs (relation frequency and magnitude) related to rainfall, runoff, and sediment yield. The results indicate two different temporal patterns: the first weather type exhibits (during the cold period: autumn and winter) westerly flows that produce the highest rainfall, runoff, and sediment yield values throughout the territory; the second weather type exhibits easterly flows that predominate during the warm period (spring and summer) and it is located on the Mediterranean coast of the Iberian Peninsula. However, the cyclonic situations present high frequency throughout the whole year with a large influence extended around the western Mediterranean basin. Contrary, the anticyclonic situations, despite of its high frequency, do not contribute significantly to the total rainfall, runoff, and sediment (showing the lowest efficiency) because of atmospheric stability that currently characterize this atmospheric pattern. Our approach helps to better understand the relationship of WTs on the seasonal and spatial variability of rainfall, runoff and sediment yield with a regional scale based on the large dataset and number of soil erosion experimental stations

Novel Simulation Approaches for Polymeric and Soft Matter Systems

Special Issue: Novel Simulation Approaches for Polymeric and Soft Matter SystemsThe last two decades have brought us a tremendous improvement in numerical methods, and the eld of computer simulations has been established as the third pillar used to increase our knowledge of natural science. As such it is of equal importance as experiments and theory in sharpening our understanding of the complex real world phenomena. It is undeniable that the increase in computer power experienced in the last two decades has enormously contributed to boost simulations. One one hand, as the computer power increases so does the ambition of the researchers to describe even more complex systems which involve large di erences in the spatial and time scales of their components. On the other hand, it is also clear that brute force alone will not pave the way to solving those issues. In the last decade the introduction of smart algorithms have been more pro table to science than the simple improvements in turn of pure CPU power. Therefore there is still an urgent and constant need for more e cient and clever algorithms, as well as for improved theoretical frameworks. Such achievements are of great interest for the scienti c community as a whole, but here in this special issue we would like to highlight achievements and novel simulation approaches to certain areas of polymeric and soft matter systems.Peer reviewe

Particle-particle particle-mesh method for dipolar interactions:on error estimates and efficiency of schemes with analytical differentiation and mesh interlacing

The interlaced and non-interlaced versions of the dipolar particle-particle particle-mesh (P3M) method implemented using the analytic differentiation scheme (AD-P3M) are presented together with their respective error estimates for the calculation of the forces, torques, and energies. Expressions for the optimized lattice Green functions, and for the Madelung self-forces, self-torques and self-energies are given. The applicability of the theoretical error estimates are thoroughly tested and confirmed in several numerical examples. Our results show that the accuracy of the calculations can be improved substantially when the approximate (mesh computed) Madelung self-interactions are subtracted. Furthermore, we show that the interlaced dipolar AD-P3M method delivers a significantly higher accuracy (which corresponds approximately to using a twice finer mesh) than the conventional method, allowing thereby to reduce the mesh size with respect to the non-interlaced version for a given accuracy. In addition, we present similar expressions for the dipolar ik-differentiation interlaced scheme, and we perform a comparison with the AD interlaced scheme. Rough tests for the relative speed of the dipolar P3M method using ik-differentiation and the interlaced/non-interlaced AD schemes show that when FFT computing time is the bottleneck, usually when working at high precisions, the interlaced AD-scheme can be several times faster than the other two schemes. For calculations with a low accuracy requirement, the interlaced version can perform worse than the ik and the non-interlaced AD schemes.All authors are grateful to the DAAD organization for providing financial support. C.H. thanks the DFG for support through the SimTech center of excellence, the ScaFaCoS collaboration, and the SFB 716, and acknowledges helpful discussions with A. Arnold and M. Pippig.Peer reviewe