Amplitude equations for systems with long-range interactions

We derive amplitude equations for interface dynamics in pattern forming systems with long-range interactions. The basic condition for the applicability of the method developed here is that the bulk equations are linear and solvable by integral transforms. We arrive at the interface equation via long-wave asymptotics. As an example, we treat the Grinfeld instability, and we also give a result for the Saffman-Taylor instability. It turns out that the long-range interaction survives the long-wave limit and shows up in the final equation as a nonlocal and nonlinear term, a feature that to our knowledge is not shared by any other known long-wave equation. The form of this particular equation will then allow us to draw conclusions regarding the universal dynamics of systems in which nonlocal effects persist at the level of the amplitude description.Comment: LaTeX source, 12 pages, 4 figures, accepted for Physical Review

Pattern formation in directional solidification under shear flow. I: Linear stability analysis and basic patterns

An asymptotic interface equation for directional solidification near the absolute stabiliy limit is extended by a nonlocal term describing a shear flow parallel to the interface. In the long-wave limit considered, the flow acts destabilizing on a planar interface. Moreover, linear stability analysis suggests that the morphology diagram is modified by the flow near the onset of the Mullins-Sekerka instability. Via numerical analysis, the bifurcation structure of the system is shown to change. Besides the known hexagonal cells, structures consisting of stripes arise. Due to its symmetry-breaking properties, the flow term induces a lateral drift of the whole pattern, once the instability has become active. The drift velocity is measured numerically and described analytically in the framework of a linear analysis. At large flow strength, the linear description breaks down, which is accompanied by a transition to flow-dominated morphologies, described in a companion paper. Small and intermediate flows lead to increased order in the lattice structure of the pattern, facilitating the elimination of defects. Locally oscillating structures appear closer to the instability threshold with flow than without.Comment: 20 pages, Latex, accepted for Physical Review

MTHFR polymorphisms involved in vitamin B12 deficiency associated with atrophic gastritis

Genetic polymorphisms affecting methylentetrahydrofolate reductase (MTHFR) activity may influence hematological and neurological dysfunction in cobalamin-deficient patients. We studied the prevalence of C677T and A1298C polymorphisms by analyzing genomic DNA in 30 cobalamin-deficient patients. No significant difference was found in 677 and 1298 genotype distribution with respect to hematological parameters, B12 and folate levels, and neurological symptoms. The two MTHFR polymorphisms were not protective against anemia or neurological dysfunction in patients with cobalamin deficiency; however, we found evidence of a significant increase in atrophic gastritis in the 677TT group (P = 0.009) but not for the 1298CC genotype. Based on observations that inadequate cobalamin intake and reduced MTHFR activity might be significant risk factors for gastric cancer, and the increased risk of gastric cancer shown in patients affected by atrophic gastritis, we speculate that concomitant atrophic gastritis and impaired MTHFR function could have a role in the development of gastric cancer

The role of MTHFR and RFC1 polymorphisms on toxicity and outcome of adult patients with hematological malignancies treated with high-dose methotrexate followed by leucovorin rescue

In the last years, the influence of different genes involved in metabolism of chemotherapeutic agents has been studied. Methotrexate (MTX) is a key compound of chemotherapeutic regimens used in the treatment of acute lymphoblastic leukemia (ALL), primary central nervous system lymphoma (PCNSL) and Burkitt's lymphomas (BL). This study aims to evaluate the role of MTHFR C677T and A1298C polymorphisms and G80A reduced folate carrier gene (RFC1) in a cohort of adult patients with lymphoproliferative malignancies submitted to high-dose MTX followed by leucovorin rescue

Incidence and trends of childhood Type 1 diabetes worldwide 1990-1999.

Aims. To examine incidence and trends of Type 1 diabetes worldwide for the period 1990–1999. Methods. The incidence of Type 1 diabetes (per 100000/year) was analysed in children aged ≤ 14 years from 114 populations in 112 centres in 57 countries. Trends in the incidence of Type 1 diabetes were analysed by fitting Poisson regression models to the dataset. Results. A total of 43013 cases were diagnosed in the study populations of 84 million children. The age-adjusted incidence of Type 1 diabetes among 112 centres (114 populations) varied from 0.1 per 100000/year in China and Venezuela to 40.9 per 100000/year in Finland. The average annual increase in incidence calculated from 103 centres was 2.8% (95% CI 2.4–3.2%). During the years 1990–1994, this increase was 2.4% (95% CI 1.3–3.4%) and during the second study period of 1995–1999 it was slightly higher at 3.4% (95% CI 2.7– 4.3%). The trends estimated for continents showed statistically significant increases all over the world (4.0% in Asia, 3.2% in Europe and 5.3% in North America), except in Central America and the West Indies where the trend was a decrease of 3.6%. Only among the European populations did the trend in incidence diminish with age. Conclusions. The rising incidence of Type 1 diabetes globally suggests the need for continuous monitoring of incidence by using standardized methods in order to plan or assess prevention strategies

Neoplasms of the genitourinary system

Nephroblastoma or Wilms’ tumor (WT) is the most common renal neoplasm in children accounting for 90 % of pediatric renal tumors (Pastore et al. 2006). It is a tumor with a good prognosis and with well-established treatment strategies. Other rare malignant renal tumors, such as clear cell sarcoma and rhabdoid tumor of the kidney, have a poor prognosis despite aggressive treatment. Renal cell carcinoma occurs in older children, while mesoblastic nephroma is the most frequent renal tumor in the neonate. Hematological malignancies, the most frequent neoplasms in children, may also involve the kidney, most often as part of a multi-organ involvement. Renal infections and malformations are much more common in children than renal tumors and may show a pseudotumoral pattern mimicking a renal tumor. In all cases, close collaboration among radiologists, pediatricians, and pathologists is essential so as to avoid diagnostic pitfalls due to atypical presentations

Core outcome set for surgical trials in gastric cancer (GASTROS study): international patient and healthcare professional consensus

Background: Surgery is the primary treatment that can offer potential cure for gastric cancer, but is associated with significant risks. Identifying optimal surgical approaches should be based on comparing outcomes from well designed trials. Currently, trials report different outcomes, making synthesis of evidence difficult. To address this, the aim of this study was to develop a core outcome set (COS)-a standardized group of outcomes important to key international stakeholders-that should be reported by future trials in this field.Methods: Stage 1 of the study involved identifying potentially important outcomes from previous trials and a series of patient interviews. Stage 2 involved patients and healthcare professionals prioritizing outcomes using a multilanguage international Delphi survey that informed an international consensus meeting at which the COS was finalized.Results: Some 498 outcomes were identified from previously reported trials and patient interviews, and rationalized into 56 items presented in the Delphi survey. A total of 952 patients, surgeons, and nurses enrolled in round 1 of the survey, and 662 (70 per cent) completed round 2. Following the consensus meeting, eight outcomes were included in the COS: disease-free survival, disease-specific survival, surgery-related death, recurrence, completeness of tumour removal, overall quality of life, nutritional effects, and 'serious' adverse events.Conclusion: A COS for surgical trials in gastric cancer has been developed with international patients and healthcare professionals. This is a minimum set of outcomes that is recommended to be used in all future trials in this field to improve trial design and synthesis of evidence

Networks beyond pairwise interactions: Structure and dynamics

The complexity of many biological, social and technological systems stems from the richness of the interactions among their units. Over the past decades, a great variety of complex systems has been successfully described as networks whose interacting pairs of nodes are connected by links. Yet, in face-to-face human communication, chemical reactions and ecological systems, interactions can occur in groups of three or more nodes and cannot be simply described just in terms of simple dyads. Until recently, little attention has been devoted to the higher-order architecture of real complex systems. However, a mounting body of evidence is showing that taking the higher-order structure of these systems into account can greatly enhance our modeling capacities and help us to understand and predict their emerging dynamical behaviors. Here, we present a complete overview of the emerging field of networks beyond pairwise interactions. We first discuss the methods to represent higher-order interactions and give a unified presentation of the different frameworks used to describe higher-order systems, highlighting the links between the existing concepts and representations. We review the measures designed to characterize the structure of these systems and the models proposed in the literature to generate synthetic structures, such as random and growing simplicial complexes, bipartite graphs and hypergraphs. We introduce and discuss the rapidly growing research on higher-order dynamical systems and on dynamical topology. We focus on novel emergent phenomena characterizing landmark dynamical processes, such as diffusion, spreading, synchronization and games, when extended beyond pairwise interactions. We elucidate the relations between higher-order topology and dynamical properties, and conclude with a summary of empirical applications, providing an outlook on current modeling and conceptual frontiers.Comment: Accepted for publication in Physics Reports. 109 pages, 47 figure