Explicit exactly energy-conserving methods for Hamiltonian systems

For Hamiltonian systems, simulation algorithms that exactly conserve numerical energy or pseudo-energy have seen extensive investigation. Most available methods either require the iterative solution of nonlinear algebraic equations at each time step, or are explicit, but where the exact conservation property depends on the exact evaluation of an integral in continuous time. Under further restrictions, namely that the potential energy contribution to the Hamiltonian is non-negative, newer techniques based on invariant energy quadratisation allow for exact numerical energy conservation and yield linearly implicit updates, requiring only the solution of a linear system at each time step. In this article, it is shown that, for a general class of Hamiltonian systems, and under the non-negativity condition on potential energy, it is possible to arrive at a fully explicit method that exactly conserves numerical energy. Furthermore, such methods are unconditionally stable, and are of comparable computational cost to the very simplest integration methods (such as Störmer-Verlet). A variant of this scheme leading to a conditionally-stable method is also presented, and follows from a splitting of the potential energy. Various numerical results are presented, in the case of the classic test problem of Fermi, Pasta and Ulam and for nonlinear systems of partial differential equations, including those describing high amplitude vibration of strings and plates

The Role of Nutrition in Primary and Secondary Prevention of Cardiovascular Damage in Childhood Cancer Survivors

Innovative therapeutic strategies in childhood cancer led to a significant reduction in cancer-related mortality. Cancer survivors are a growing fragile population, at risk of long-term side effects of cancer treatments, thus requiring customized clinical attention. Antineoplastic drugs have a wide toxicity profile that can limit their clinical usage and spoil patients' life, even years after the end of treatment. The cardiovascular system is a well-known target of antineoplastic treatments, including anthracyclines, chest radiotherapy and new molecules, such as tyrosine kinase inhibitors. We investigated nutritional changes in children with cancer from the diagnosis to the end of treatment and dietary habits in cancer survivors. At diagnosis, children with cancer may present variable degrees of malnutrition, potentially affecting drug tolerability and prognosis. During cancer treatment, the usage of corticosteroids can lead to rapid weight gain, exposing children to overweight and obesity. Moreover, dietary habits and lifestyle often dramatically change in cancer survivors, who acquire sedentary behavior and weak adherence to dietary guidelines. Furthermore, we speculated on the role of nutrition in the primary prevention of cardiac damage, investigating the potential cardioprotective role of diet-derived compounds with antioxidative properties. Finally, we summarized practical advice to improve the dietary habits of cancer survivors and their families

Activity of a Pediatric Emergency Department of a Tertiary Center in Bologna, Italy, during SARS-CoV-2 Pandemic

During the SARS-CoV-2 pandemic, the pediatric emergency department (ED) of Bologna, Emilia-Romagna, Italy faced a reorganization to better deal with the new clinical needs. We herein describe the main changes in the organization and in the attendances to our pediatric ED. From the 1 March 2020 to the 31 January 2022, 796 children positive for SARS-CoV-2 presented to our pediatric ED, but only 26 required hospitalizations, of which only 9 for COVID-19 related reasons. During this period, we also registered a temporal correlation between multisystem inflammatory syndrome in children (MIS-C) admissions and the peaks of SARS-CoV-2 infection in the Italian population. Respiratory syncytial virus (RSV) remained during last year the viral infection with the highest hospitalization rate. The analysis and description of the changes in the activity of the pediatric ED during the SARS-CoV-2 pandemic may help to better understand the routinary activity and be prepared for any possible new challenge

The Relationship between Gut Microbiota and Respiratory Tract Infections in Childhood: A Narrative Review

Respiratory tract infections (RTIs) are common in childhood and represent one of the main causes of hospitalization in this population. In recent years, many studies have described the association between gut microbiota (GM) composition and RTIs in animal models. In particular, the “inter-talk” between GM and the immune system has recently been unveiled. However, the role of GM in human, and especially infantile, RTIs has not yet been fully established. In this narrative review we provide an up-to-date overview of the physiological pathways that explain how the GM shapes the immune system, potentially influencing the response to common childhood respiratory viral infections and compare studies analysing the relationship between GM composition and RTIs in children. Most studies provide evidence of GM dysbiosis, but it is not yet possible to identify a distinct bacterial signature associated with RTI predisposition. A better understanding of GM involvement in RTIs could lead to innovative integrated GM-based strategies for the prevention and treatment of RTIs in the paediatric population

Enteral nutrition protects children undergoing allogeneic hematopoietic stem cell transplantation from blood stream infections

Enteral Nutrition (EN) is recommended as first line nutritional support for patients undergoing Allogeneic Hematopoietic Stem Cell Transplantation (allo-HSCT), but only few studies exist in the literature which compare EN to Parenteral Nutrition (PN) in the paediatric population. Forty-two consecutive paediatric patients undergoing allo-HSCT at our referral centre between January 2016 and July 2019 were evaluated. Post-transplant and nutritional outcomes of patients receiving EN for more than 7 days (EN group, n = 14) were compared with those of patients receiving EN for fewer than 7 days or receiving only PN (PN group, n = 28). In the EN group, a reduced incidence of Blood Stream Infections (BSI) was observed (p = 0.02) (n = 2 vs. n = 15; 14.3% vs. 53.6%). The type of nutritional support was also the only variable independently associated with BSI in the multivariate analysis (p = 0.03). Platelet engraftment was shorter in the PN group than in the EN group for a threshold of > 20*109/L (p = 0.04) (23.1 vs 35.7 days), but this correlation was not confirmed with a threshold of > 50*109/L. The Body Mass Index (BMI) and the BMI Z-score were no different in the two groups from admission to discharge. Our results highlight that EN is a feasible and nutritionally adequate method of nutritional support for children undergoing allo-HSCT in line with the present literature. Future functional studies are needed to better address the hypothesis that greater intestinal eubyosis maintained with EN may explain the observed reduction in BSI

In‐Depth Immunological Typization of Children with Sickle Cell Disease: A Preliminary Insight into Its Plausible Correlation with Clinical Course and Hydroxyurea Therapy

Sickle cell disease (SCD) is a condition of functional hypo‐/a‐splenism in which predisposition to bacterial infections is only a facet of a wide spectrum of immune‐dysregulation disorders forming the clinical expression of a peculiar immunophenotype. The objective of this study was to perform an in‐depth immunophenotypical characterization of SCD pediatric patients, looking for plausible correlations between immunological biomarkers, the impact of hydroxyurea (HU) treatment and clinical course. This was an observational case–control study including 43 patients. The cohort was divided into two main groups, SCD subjects (19/43) and controls (24/43), differing in the presence/absence of an SCD diagnosis. The SCD group was split up into HU+ (12/19) and HU− (7/19) subgroups, respectively receiving or not a concomitant HU treatment. The principal outcomes measured were differences in the immunophenotyping between SCD patients and controls through chi‐squared tests, t‐tests, and Pearson’s correlation analysis between clinical and immunological parameters. Leukocyte and neutrophil increase, T‐cell depletion with prevalence of memory T‐cell compartment, NK and B‐naïve subset elevation with memory and CD21low B subset reduction, and IgG expansion, significantly distinguished the SCD HU− subgroup from controls, with naïve T cells, switched‐memory B cells and IgG maintaining differences between the SCD HU+ group and controls (p‐value of <0.05). The mean CD4+ central‐memory T‐cell% count was the single independent variable showing a positive correlation with vaso‐occlusive crisis score in the SCD group (Pearson’s R = 0.039). We report preliminary data assessing plausible clinical implications of baseline and HU‐related SCD immunophenotypical alterations, which need to be validated in larger samples, but potentially affecting hypo‐/a‐splenism immuno‐chemoprophylactic recommendations

Visceral Leishmaniasis: Epidemiology, Diagnosis, and Treatment Regimens in Different Geographical Areas with a Focus on Pediatrics

Visceral Leishmaniasis (VL) is a vector-borne disease caused by an intracellular protozoa of the genus Leishmania that can be lethal if not treated. VL is caused by Leishmania donovani in Asia and in Eastern Africa, where the pathogens’ reservoir is represented by humans, and by Leishmania infantum in Latin America and in the Mediterranean area, where VL is a zoonotic disease and dog is the main reservoir. A part of the infected individuals become symptomatic, with irregular fever, splenomegaly, anemia or pancytopenia, and weakness, whereas others are asymptomatic. VL treatment has made progress in the last decades with the use of new drugs such as liposomal amphotericin B, and with new therapeutic regimens including monotherapy or a combination of drugs, aiming at shorter treatment duration and avoiding the development of resistance. However, the same treatment protocol may not be effective all over the world, due to differences in the infecting Leishmania species, so depending on the geographical area. This narrative review presents a comprehensive description of the clinical picture of VL, especially in children, the diagnostic approach, and some insight into the most used pharmacological therapies available worldwide

Consideration of damages of a floating roof-type oil storage tank due to thermal stress

Several cracks were found on some actual floating roofs of the crude oil tanks in a southern Japan refinery. It was assumed that one of the causes is due to thermal stress during the day. In order to figure out whether the thermal stress could cause damage on the floating roof, strain and temperature were measured on the actual floating roof by using optical fiber gauges. Furthermore, thermal stress analysis and fracture possibility estimation were also carried out as additional analysis. As a result, thermal stress on the floating roof turned to be relatively small and could not cause the initial crack. However, the temperature fluctuation in a day could affect the crack propagatio

Gut resistome plasticity in pediatric patients undergoing hematopoietic stem cell transplantation

The gut microbiome of pediatric patients undergoing allo-hematopoietic stem cell transplantation (HSCT) has recently been considered as a potential reservoir of antimicrobial resistance, with important implications in terms of patient mortality rate. By means of shotgun metagenomics, here we explored the dynamics of the gut resistome \u2013 i.e. the pattern of antibiotic resistance genes provided by the gut microbiome \u2013 in eight pediatric patients undergoing HSCT, half of whom developed acute Graft-versus-Host Disease (aGvHD). According to our findings, the patients developing aGvHD are characterized by post-HSCT expansion of their gut resistome, involving the acquisition of new resistances, as well as the consolidation of those already present before HSCT. Interestingly, the aGvHD-associated bloom in resistome diversity is not limited to genes coding for resistance to the antibiotics administered along the therapeutic course, but rather involves a broad pattern of different resistance classes, including multidrug resistance, as well as resistance to macrolides, aminoglycosides, tetracyclines and beta-lactams. Our data stress the relevance of mapping the gut resistome in HSCT pediatric patients to define the most appropriate anti-infective treatment post HSCT