Centrality Measures in Spatial Networks of Urban Streets

We study centrality in urban street patterns of different world cities represented as networks in geographical space. The results indicate that a spatial analysis based on a set of four centrality indices allows an extended visualization and characterization of the city structure. Planned and self-organized cities clearly belong to two different universality classes. In particular, self-organized cities exhibit scale-free properties similar to those found in the degree distributions of non-spatial networks.Comment: 4 pages, 3 figure

A model for cascading failures in complex networks

Large but rare cascades triggered by small initial shocks are present in most of the infrastructure networks. Here we present a simple model for cascading failures based on the dynamical redistribution of the flow on the network. We show that the breakdown of a single node is sufficient to collapse the efficiency of the entire system if the node is among the ones with largest load. This is particularly important for real-world networks with an highly hetereogeneous distribution of loads as the Internet and electrical power grids.Comment: 4 pages, 4 figure

Autotetraploid Emergence via Somatic Embryogenesis in Vitis vinifera Induces Marked Morphological Changes in Shoots, Mature Leaves, and Stomata

Polyploidy plays an important role in plant adaptation to biotic and abiotic stresses. Alterations of the ploidy in grapevine plants regenerated via somatic embryogenesis (SE) may provide a source of genetic variability useful for the improvement of agronomic characteristics of crops. In the grapevine, the SE induction process may cause ploidy changes without alterations in DNA profile. In the present research, tetraploid plants were observed for 9.3% of 'Frappato' grapevine somatic embryos regenerated in medium supplemented with the growth regulators β-naphthoxyacetic acid (10 µM) and N6-benzylaminopurine (4.4 µM). Autotetraploid plants regenerated via SE without detectable changes in the DNA profiles were transferred in field conditions to analyze the effect of polyploidization. Different ploidy levels induced several anatomical and morphological changes of the shoots and mature leaves. Alterations have been also observed in stomata. The length and width of stomata of tetraploid leaves were 39.9 and 18.6% higher than diploids, respectively. The chloroplast number per guard cell pair was higher (5.2%) in tetraploid leaves. On the contrary, the stomatal index was markedly decreased (12%) in tetraploid leaves. The observed morphological alterations might be useful traits for breeding of grapevine varieties in a changing environment

Abnormal illness behavior and Internet addiction severity: The role of disease conviction, irritability, and alexithymia

Background and aims: While the association between health anxiety and maladaptive Internet use is a well-established finding, no studies have been performed to examine the possible effect of abnormal illness behavior (AIB). AIB is a maladaptive manner of experiencing, evaluating, or acting in response to health and illness that is disproportionate to evident pathology. The aim of this study was to investigate the association between AIB and Internet addiction (IA) severity in a sample of Italian University students. The possible effect of alexithymia, anxiety, and depression was also taken into account. Methods: Participants were 115 men and 163 women (mean age = 23.62 - 4.38 years); AIB was measured via the Illness Behavior Questionnaire (IBQ), and IA severity by the Internet Addiction Test (IAT). Results: The most powerful IBQ factor predicting IA severity scores was disease conviction. Irritability was the only emotional IBQ factor associated with IA severity. Nevertheless, disease conviction and alexithymia remained the only significant predictors of IAT scores when hierarchical regression analysis was executed. Discussion and conclusions: Our results support previous findings showing that those characterized by health anxiety are more prone to an excessive and maladaptive use of Internet. Moreover, this study showed that irritability was the only emotional aspect of AIB predicting IA severity. This finding is consistent with the cognitive model of hypochondria, which states that cognitive factors (dysfunctional beliefs and assumptions) play a major role in the explanation of this psychopathological condition

Quantitative analysis of basic fibroblast growth factor and vascular endothelial growth factor in human colorectal cancer.

Tumour growth is angiogenesis dependent. Some authors suggest a prognostic role of microvessel count in colorectal cancer. We tested the role of basic fibroblast growth factor (bFGF) and vascular endothelial growth factor (VEGF) in the switch to the angiogenic phenotype in 35 patients with colorectal cancer at different stages of disease. We evaluated the two angiogenic factors, by enzyme-linked immunosorbent assay (ELISA), in tumour, peritumoral mucosa, pathological mesenteric and peripheral blood. We used ten endoscopic intestinal biopsies and ten peripheral blood samples from healthy subjects as control. bFGF was significantly lower in tumour tissues and in peritumoral mucosas than in healthy mucosas, whereas VEGF was up-regulated in tumours but not in peritumoral mucosa. Both angiogenic factors were greatly increased in mesenteric blood. VEGF tumour and serum levels were significantly correlated with the stage of disease. bFGF tumour and serum concentration were not correlated with the stage of disease. The high levels of bFGF in mesenteric blood suggest that this growth factor might be abnormally released from tumour tissue and peritumoral mucosa and could function as an early effector in the switch to the angiogenic phenotype. In contrast, VEGF, whose levels show a significant correlation with the stage of disease, could act in a following step, supporting tumour progression

Duodenal Malignant Somatostatinoma

The authors report a case of hormonally silent duodenal somatostatinoma. The main clinical features, the natural history and the currently available therapies of these rare neoplasms are described on the basis of this case and of the scientific literature. Although the antiblastic therapies are still debated, the patient showed a surprising outcome following chemotherapy

How big is too big? Critical Shocks for Systemic Failure Cascades

External or internal shocks may lead to the collapse of a system consisting of many agents. If the shock hits only one agent initially and causes it to fail, this can induce a cascade of failures among neighoring agents. Several critical constellations determine whether this cascade remains finite or reaches the size of the system, i.e. leads to systemic risk. We investigate the critical parameters for such cascades in a simple model, where agents are characterized by an individual threshold \theta_i determining their capacity to handle a load \alpha\theta_i with 1-\alpha being their safety margin. If agents fail, they redistribute their load equally to K neighboring agents in a regular network. For three different threshold distributions P(\theta), we derive analytical results for the size of the cascade, X(t), which is regarded as a measure of systemic risk, and the time when it stops. We focus on two different regimes, (i) EEE, an external extreme event where the size of the shock is of the order of the total capacity of the network, and (ii) RIE, a random internal event where the size of the shock is of the order of the capacity of an agent. We find that even for large extreme events that exceed the capacity of the network finite cascades are still possible, if a power-law threshold distribution is assumed. On the other hand, even small random fluctuations may lead to full cascades if critical conditions are met. Most importantly, we demonstrate that the size of the "big" shock is not the problem, as the systemic risk only varies slightly for changes of 10 to 50 percent of the external shock. Systemic risk depends much more on ingredients such as the network topology, the safety margin and the threshold distribution, which gives hints on how to reduce systemic risk.Comment: 23 pages, 7 Figure

WRKY Gene Family Drives Dormancy Release in Onion Bulbs

Onion (Allium cepa L.) is an important bulb crop grown worldwide. Dormancy in bulbous plants is an important physiological state mainly regulated by a complex gene network that determines a stop of vegetative growth during unfavorable seasons. Limited knowledge on the molecular mechanisms that regulate dormancy in onion were available until now. Here, a comparison between uninfected and onion yellow dwarf virus (OYDV)-infected onion bulbs highlighted an altered dormancy in the virus-infected plants, causing several symptoms, such as leaf striping, growth reduction, early bulb sprouting and rooting, as well as a lower abscisic acid (ABA) level at the start of dormancy. Furthermore, by comparing three dormancy stages, almost five thousand four hundred (5390) differentially expressed genes (DEGs) were found in uninfected bulbs, while the number of DEGs was significantly reduced (1322) in OYDV-infected bulbs. Genes involved in cell wall modification, proteolysis, and hormone signaling, such as ABA, gibberellins (GAs), indole3-acetic acid (IAA), and brassinosteroids (BRs), that have already been reported as key dormancyrelated pathways, were the most enriched ones in the healthy plants. Interestingly, several transcription factors (TFs) were up-regulated in the uninfected bulbs, among them three genes belonging to the WRKY family, for the first time characterized in onion, were identified during dormancy release. The involvement of specific WRKY genes in breaking dormancy in onion was confirmed by GO enrichment and network analysis, highlighting a correlation between AcWRKY32 and genes driving plant development, cell wall modification, and division via gibberellin and auxin homeostasis, two key processes in dormancy release. Overall, we present, for the first time, a detailed molecular analysis of the dormancy process, a description of the WRKY-TF family in onion, providing a better understanding of the role played by AcWRKY32 in the bulb dormancy release. The TF coexpressed genes may represent targets for controlling the early sprouting in onion, laying the foundations for novel breeding programs to improve shelf life and reduce postharvest

RAMAN spectroscopy imaging improves the diagnosis of papillary thyroid carcinoma

Recent investigations strongly suggest that Raman spectroscopy (RS) can be used as a clinical tool in cancer diagnosis to improve diagnostic accuracy. In this study, we evaluated the efficiency of Raman imaging microscopy to discriminate between healthy and neoplastic thyroid tissue, by analyzing main variants of Papillary Thyroid Carcinoma (PTC), the most common type of thyroid cancer. We performed Raman imaging of large tissue areas (from 100 × 100 μm2 up to 1 × 1 mm2), collecting 38 maps containing about 9000 Raman spectra. Multivariate statistical methods, including Linear Discriminant Analysis (LDA), were applied to translate Raman spectra differences between healthy and PTC tissues into diagnostically useful information for a reliable tissue classification. Our study is the first demonstration of specific biochemical features of the PTC profile, characterized by significant presence of carotenoids with respect to the healthy tissue. Moreover, this is the first evidence of Raman spectra differentiation between classical and follicular variant of PTC, discriminated by LDA with high efficiency. The combined histological and Raman microscopy analyses allow clear-cut integration of morphological and biochemical observations, with dramatic improvement of efficiency and reliability in the differential diagnosis of neoplastic thyroid nodules, paving the way to integrative findings for tumorigenesis and novel therapeutic strategies