The Severi inequality K2≥4χK^2\ge 4\chi for surfaces of maximal Albanese dimension

We prove the so-called Severi inequality, stating that the invariants of a minimal smooth complex projective surface of maximal Albanese dimension satisfy: K^2_S >= 4\chi(S).Comment: Final version: proof slightly simplified, a reference adde

Recent advances in understanding and managing diverticulitis.

In the past few decades, the increasing socioeconomic burden of acute diverticulitis (AD) has become evident, and with the growth of the population age, this significant economic impact will likely continue to rise. Furthermore, recent evidence showed an increased rate of hospital admissions especially evident among women and younger individuals. The natural history and pathophysiology of this clinical condition is still to be fully defined, and efforts continue to be made in the identification of risk factors and the establishment of relative preventive strategies. The actual therapeutic strategies aimed to modulate gut microbiota, such as rifaximin or probiotics, or to reduce mucosal inflammation, such as mesalazine, present a relatively poor efficacy for both the prevention of the first AD episode (primary prevention) and its recurrence (secondary prevention). In the last few years, the main goal achieved has been in the management of AD in that uncomplicated AD can, to a larger extent, be managed in an outpatient setting with no or little supportive therapy, a strategy that will certainly impact on the health costs of this disease. The problem of AD recurrence remains a topic of debate. The aim of this review is to present updated evidence on AD epidemiology and relative open clinical questions and to analyze in detail predisposing and protective factors with an attempt to integrate their possible modes of action into the several pathogenic mechanisms that have been suggested to contribute to this multifactorial disease. A unifying hypothesis dealing with the colonic luminal and extra-luminal microenvironments separately is provided. Finally, evidence-based changes in therapeutic management will be summarized. Because of an ascertained multifactorial pathogenesis of uncomplicated and complicated AD, it is probable that a single ‘causa prima’ will not be identifiable, and a better stratification of patients could allow one to pursue tailored therapeutic algorithm strategies

On the structural nature of cooperation in distributed network localization

We demonstrate analytically that the contribution of cooperation in improving the accuracy of distributed network localization has a fundamentally structural nature, rather then statistical as widely believed. To this end we first introduce a new approach to build Fisher Information Matrices (FIMs), in which the individual contribution of each cooperative pair of nodes is captured explicitly by a corresponding information vector. The approach offers new insight onto the structure of FIMs, enabling us to easily account for both anchor and node location uncertainties in assessing lower bounds on localization errors. Using this construction it is surprisingly found that in the presence of node location uncertainty and regardless of ranging error variances or network size, the Fisher information matrix (FIM) terms corresponding to the information added by node-to-node cooperation nearly vanish. In other words, the analysis reveals that the key contribution of cooperation in network localization is not to add statistical node-to-node information (in the Fisher sense), but rather to provide a structure over which information is better exploited

Gastrointestinal neuromuscular apparatus: An underestimated target of gut microbiota

Over the last few years, the importance of the resident intestinal microbiota in the pathogenesis of several gastro- intestinal diseases has been largely investigated. Growing evidence suggest that microbiota can influence gastro- intestinal motility. The current working hypothesis is that dysbiosis-driven mucosal alterations induce the production of several inflammatory/immune mediators which affect gut neuro-muscular functions. Besides these indirect mucosal-mediated effects, the present review highlights that recent evidence suggests that microbiota can directly affect enteric nerves and smooth muscle cells functions through its metabolic products or bacterial molecular components translocated from the intestinal lumen. Toll- like receptors, the bacterial recognition receptors, are expressed both on enteric nerves and smooth muscle and are emerging as potential mediators between microbiota and the enteric neuromuscular apparatus. Furthermore, the ongoing studies on probiotics support the hypothesis that the neuromuscular apparatus may represent a target of intervention, thus opening new physiopathological and therapeutic scenarios

Second to fourth digit ratio (2D:4D) and concentrations of circulating sex hormones in adulthood

BACKGROUND: The second to fourth digit ratio (2D:4D) is used as a marker of prenatal sex hormone exposure. The objective of this study was to examine whether circulating concentrations of sex hormones and SHBG measured in adulthood was associated with 2D:4D. METHODS: This analysis was based on a random sample from the Melbourne Collaborative Cohort Study. The sample consisted of of 1036 men and 620 post-menopausal women aged between 39 and 70 at the time of blood draw. Concentrations of circulating sex hormones were measured from plasma collected at baseline (1990-1994), while digit length was measured from hand photocopies taken during a recent follow-up (2003-2009). The outcome measures were circulating concentrations of testosterone, oestradiol, dehydroepiandrosterone sulphate, androstenedione, Sex Hormone Binding Globulin, androstenediol glucoronide for men only and oestrone sulphate for women only. Free testosterone and oestradiol were estimated using standard formulae derived empirically. Predicted geometric mean hormone concentrations (for tertiles of 2D:4D) and conditional correlation coefficients (for continuous 2D:4D) were obtained using mixed effects linear regression models. RESULTS: No strong associations were observed between 2D:4D measures and circulating concentrations of hormones for men or women. For males, right 2D:4D was weakly inversely associated with circulating testosterone (predicted geometric mean testosterone was 15.9 and 15.0 nmol/L for the lowest and highest tertiles of male right 2D:4D respectively (P-trend = 0.04). There was a similar weak association between male right 2D:4D and the ratio of testosterone to oestradiol. These associations were not evident in analyses of continuous 2D:4D. CONCLUSIONS: There were no strong associations between any adult circulating concentration of sex hormone or SHGB and 2D:4D. These results contribute to the growing body of evidence indicating that 2D:4D is unrelated to adult sex hormone concentrations

A case of Barrett's oesophagus in pernicious anaemia: acid is not the only culprit!

A 46-year-old female presented at our department with the onset of episodic dyspeptic symptoms, mainly postprandial fullness and bloating, as well as paresthesia. A blood test revealed the presence of mild macrocytic anaemia (haemoglobin 11.3 g/dl; mean corpuscular volume 119 fl), a reduced level of vitamin B12 (60 pmol/l; normal 200–750 pmol/l), hypergastrinaemia (1363 pg/ml; normal for female <100 pg/ml), a low level of pepsinogen I (<2.6 pg/ml; normal 30–100 pg/ml), and positivity for antibodies against parietal cells (>1:100). The upper endoscopy showed in oesophagus a single linear erosion (grade A according to Los Angeles Classification), with an absence of macroscopic gastric abnormalities. At histology, mucosal severe atrophy with moderate intestinal metaplasia was found in fundus and gastric corpus with spared antrum, in the absence of Helicobacter pylori infection. A diagnosis of autoimmune gastritis with pernicious anaemia was therefore made, and the patient started vitamin B12 intramuscular injections. Due to the absence of specific symptoms such as heartburn and/or regurgitation and to the presence of autoimmune gastritis, the erosive oesophagitis was not treated. After 4 weeks of treatment with vitamin B12, the haemoglobin, mean corpuscular volume and vitamin B12 values were restored, paresthesia improved, while dyspepsia remained stable, with sporadic symptoms about once a week

Giocare con la luce. Idee per attività di osservazione ed esplorazione

pp.57-75Con le attività che presentiamo in questo capitolo ci si propone di studiare alcuni aspetti fisici della luce partendo da osservazioni di fatti del mondo di ogni giorno, come per esempio riconoscere gli effetti dovuti alla propagazione rettilinea della luce, collegare la scomposizione della luce bianca ai colori, individuare varie situazioni della percezione delle immagini. Le esperienze suggerite sono tutte realizzabili con materiali "poveri" che fanno parte del mondo quotidiano dei bambini e che, oltre a costare poco, non li spaventano ed anzi li invitano ad assumere l'abitudine di porsi delle domande sulle cose che li circondano.With the activities we present in this chapter, we intend to study some physical aspects of light from observations of everyday world events, such as recognizing the effects of the direct propagation of light, linking the white light to the color , to identify various situations of image perception. Suggested experiences are all feasible with "poor" materials that are part of the everyday world of children and that, in addition to cost a little, they do not frighten them and even invite them to take the habit of asking questions about the things around them