10,908 research outputs found

    Non-collaborative Attackers and How and Where to Defend Flawed Security Protocols (Extended Version)

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    Security protocols are often found to be flawed after their deployment. We present an approach that aims at the neutralization or mitigation of the attacks to flawed protocols: it avoids the complete dismissal of the interested protocol and allows honest agents to continue to use it until a corrected version is released. Our approach is based on the knowledge of the network topology, which we model as a graph, and on the consequent possibility of creating an interference to an ongoing attack of a Dolev-Yao attacker, by means of non-collaboration actuated by ad-hoc benign attackers that play the role of network guardians. Such guardians, positioned in strategical points of the network, have the task of monitoring the messages in transit and discovering at runtime, through particular types of inference, whether an attack is ongoing, interrupting the run of the protocol in the positive case. We study not only how but also where we can attempt to defend flawed security protocols: we investigate the different network topologies that make security protocol defense feasible and illustrate our approach by means of concrete examples.Comment: 29 page

    Trapping and patterning of biological objects using photovoltaic tweezers

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    Photovoltaic tweezers are a recently proposed technique for manipulation and patterning of micro- and nano-objects. It is based in the dielectrophoretic forces associated to the electric fields induced by illumination of certain ferroelectrics due to the bulk photovoltaic effect. The technique has been applied to the patterning of dielectric and metal micro- and nano-particles. In this work, we report the use of photovoltaic tweezers to pattern biological objects on LiNbO3:Fe. Specifically, spores and pollen grains and their nanometric fragments have been trapped and patterned. 1D and 2D arrangements have been achieved by deposition in air or from a hexane suspension. The quality of patterns obtained with nanometric fragments is even better than previous results using photovoltaic tweezers with inorganic micro- and nano-particles. In fact, 1D patterns with a period of 2 μm, almost half of the minimum reported period achieved with photovoltaic tweezers, have been obtained with pollen fragmentsThis work was supported by Spanish projects MAT2011-28379-C03 and MAT2014-57704-C0

    Canine Mesenchymal Stem Cells from visceral and subcutaneuous adipose tissue for cell-based therapy

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    This study compared some characteristics of canine Adipose tissue-Derived Mesenchymal Stem Cells (cAD-MSCs) from subcutaneous and visceral fat. These findings were directed to obtain high quantity and quality cAD-MSCs for clinical cell-based therapy

    An innovative method for the detection of contaminant viral genome in cell cultures

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    The use of cell cultures involves different fields of biology, from diagnosis to research. Moreover, technologies based on animal cells represent a useful tool to the development of biological products for the prophylaxis and therapy in humans and animals. Therefore, it is necessary to perform quality controls, including virological tests. Several tests performed in research laboratories are able to discriminate one or more viral species, but it is not possible to demonstrate the presence of contaminant viral genome with one non-specific method. The aim of this work consisted on the realization of a biomolecular method able to detect and to identify by sequencing extraneous viral genome in cell cultures of animal and human origin in the absence of any specific information about the virus

    Aerobic training and angiogenesis activation in patients with stable chronic heart failure: a preliminary report.

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    The pathophysiology of chronic heart failure (CHF) involves multiple hystologic and molecular alterations. To determine the effects of physical training on circulating endothelial progenitor cells (EPCs), angiogenesis (angiogenin, angiopoietin-1 and -2, VEGF, Tie-2, SDF-1α) and inflammation (IL-6, CRP), we compared data obtained from 11 CHF pts before and after 3 months aerobic exercise training, to those from 10 non trained CHF pts (CHF-C group, age 64 + 2 years, NYHA 2). At the end of the study, EPCs count and AP-2 serum levels significantly increased in the CHF-TR group. These preliminary data suggest a significant effect of even a short program of physical training on angiogenic activation and endothelial dysfunction

    A new fluorescence reaction in DNA cytochemistry: Microscopic and spectroscopic studies on the aromatic diamidino compound M&B 938

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    We describe the fluorescence properties and cytochemical applications of the aromatic diamidine M&B 938. Treatment of cell smears (chicken blood, Ehrlich ascites tumor, rat bone marrow, mouse mast cells, and Trypanosoma cruzi epimastigotes) with aqueous solutions of M&B 938 (0.5–1 μg/ml at pH 6–7; UV excitation) induced bright bluish-white fluorescence in DNA-containing structures (interphase and mitotic chromatin, AT-rich kinetoplast DNA of T. cruzi), which was abolished by previous DNA extraction. DNA was the unique fluorescent polyanion after staining with M&B 938 at neutral or alkaline pH, other polyanions such as RNA and heparin showing no emission. M&B 938-stained mouse metaphase chromosomes revealed high fluorescence of the AT-rich centromeric heterochromatin, and strong emission of heterochromatin in human chromosomes 1, 9, 15, 16, and Y was found after distamycin A counterstaining. On agarose gel electrophoresis, M&B 938-stained DNA markers appeared as fluorescent bands. The 1.635-kBP fragment from DNA ladder revealed a higher emission value than that expected from linear regression analysis. Spectroscopic studies showed bathochromic and hyperchromic shifts in the absorption spectrum of M&B 938 complexed with DNA, as well as strong enhancement of fluorescence at 420 nm. In the presence of poly(dA)-poly(dT), the emission of M&B 938 was 4.25-fold higher than with DNA; no fluorescence was observed with poly(dG)-poly(dC). Experimental results and considerations of the chemical structure suggest that the minor groove of AT regions of DNA could be the specific binding site for M&B 938, which shows interesting properties and useful applications as a new DNA fluorochrome

    Evolution of Linear Absorption and Nonlinear Optical Properties in V-Shaped Ruthenium(II)-Based Chromophores

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    In this article, we describe a series of complexes with electron-rich cis-{Ru^(II)(NH_3)_4}^(2+) centers coordinated to two pyridyl ligands bearing N-methyl/arylpyridinium electron-acceptor groups. These V-shaped dipolar species are new, extended members of a class of chromophores first reported by us (Coe, B. J. et al. J. Am. Chem. Soc. 2005, 127, 4845−4859). They have been isolated as their PF_6− salts and characterized by using various techniques including ^1H NMR and electronic absorption spectroscopies and cyclic voltammetry. Reversible Ru^(III/II) waves show that the new complexes are potentially redox-switchable chromophores. Single crystal X-ray structures have been obtained for four complex salts; three of these crystallize noncentrosymmetrically, but with the individual molecular dipoles aligned largely antiparallel. Very large molecular first hyperpolarizabilities β have been determined by using hyper-Rayleigh scattering (HRS) with an 800 nm laser and also via Stark (electroabsorption) spectroscopic studies on the intense, visible d → π^* metal-to-ligand charge-transfer (MLCT) and π → π^* intraligand charge-transfer (ILCT) bands. The latter measurements afford total nonresonant β_0 responses as high as ca. 600 × 10^(−30) esu. These pseudo-C_(2v) chromophores show two substantial components of the β tensor, β_(zzz) and β_(zyy), although the relative significance of these varies with the physical method applied. According to HRS, β_(zzz) dominates in all cases, whereas the Stark analyses indicate that β_(zyy) is dominant in the shorter chromophores, but β_(zzz) and β_(zyy) are similar for the extended species. In contrast, finite field calculations predict that β_(zyy) is always the major component. Time-dependent density functional theory calculations predict increasing ILCT character for the nominally MLCT transitions and accompanying blue-shifts of the visible absorptions, as the ligand π-systems are extended. Such unusual behavior has also been observed with related 1D complexes (Coe, B. J. et al. J. Am. Chem. Soc. 2004, 126, 3880−3891)

    Has VZV epidemiology changed in Italy? Results of a seroprevalence study

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    The aim of the study was to evaluate if and how varicella prevalence has changed in Italy. In particular a seroprevalence study was performed, comparing it to similar surveys conducted in pre-immunization era. During 2013–2014, sera obtained from blood samples taken for diagnostic purposes or routine investigations were collected in collaboration with at least one laboratory/center for each region, following the approval of the Ethics Committee. Data were stratified by sex and age. All samples were processed in a national reference laboratory by an immunoassay with high sensitivity and specificity. Statutory notifications, national hospital discharge database and mortality data related to VZV infection were analyzed as well. A total of 3707 sera were collected and tested. In the studied period both incidence and hospitalization rates decreased and about 5 deaths per year have been registered. The seroprevalence decreased in the first year of life in subjects passively protected by their mother, followed by an increase in the following age classes. The overall antibody prevalence was 84%. The comparison with surveys conducted with the same methodology in 1996–1997 and 2003–2004 showed significant differences in age groups 1–19 y. The study confirms that in Italy VZV infection typically occurs in children. The impact of varicella on Italian population is changing. The comparison between studies performed in different periods shows a significant increase of seropositivity in age class 1–4 years, expression of vaccine interventions already adopted in some regions

    Magnetic resonance imaging in the prenatal diagnosis of neural tube defects

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    OBJECTIVE: To assess the role of magnetic resonance imaging (MRI) in the prenatal diagnosis of neural tube defects (NTDs). BACKGROUND: NTDs comprise a heterogeneous group of congenital anomalies that derive from the failure of the neural tube to close. Advances in ultrasonography and MRI have considerably improved the diagnosis and treatment of NTDs both before and after birth. Ultrasonography is the first technique in the morphological study of the fetus, and it often makes it possible to detect or suspect NTDs. Fetal MRI is a complementary technique that makes it possible to clear up uncertain ultrasonographic findings and to detect associated anomalies that might go undetected at ultrasonography. The progressive incorporation of intrauterine treatments makes an accurate diagnosis of NTDs essential to ensure optimal perinatal management. The ability of fetal MRI to detect complex anomalies that affect different organs has been widely reported, and it can be undertaken whenever NTDs are suspected. CONCLUSION: We describe the normal appearance of fetal neural tube on MRI, and we discuss the most common anomalies involving the structures and the role of fetal MRI in their assessment. KEY POINTS: • To learn about the normal anatomy of the neural tube on MRI • To recognise the MR appearance of neural tube defects • To understand the value of MRI in assessing NTD
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