2,672 research outputs found

    A Study on Secret Key Rate in Wideband Rice Channel

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    Standard cryptography is expected to poorly fit IoT applications and services, as IoT devices can hardly cope with the computational complexity often required to run encryption algorithms. In this framework, physical layer security is often claimed as an effective solution to enforce secrecy in IoT systems. It relies on wireless channel characteristics to provide a mechanism for secure communications, with or even without cryptography. Among the different possibilities, an interesting solution aims at exploiting the random-like nature of the wireless channel to let the legitimate users agree on a secret key, simultaneously limiting the eavesdropping threat thanks to the spatial decorrelation properties of the wireless channel. The actual reliability of the channel-based key generation process depends on several parameters, as the actual correlation between the channel samples gathered by the users and the noise always affecting the wireless communications. The sensitivity of the key generation process can be expressed by the secrecy key rate, which represents the maximum number of secret bits that can be achieved from each channel observation. In this work, the secrecy key rate value is computed by means of simulations carried out under different working conditions in order to investigate the impact of major channel parameters on the SKR values. In contrast to previous works, the secrecy key rate is computed under a line-of-sight wireless channel and considering different correlation levels between the legitimate users and the eavesdropper

    Prospective study of a molecular selection profile for RAS wild type colorectal cancer patients receiving irinotecan-cetuximab

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    Background: The aim of our study was to evaluate whether a panel of biomarkers, prospectively analysed might be able to predict patients' clinical outcome more accurately than RAS status alone. Methods: K-RAS (exons 2, 3, 4) wild type colorectal cancer patients, candidates to second/third-line cetuximab with chemotherapy were prospectively allocated into 2 groups on the basis of their profile: favourable (BRAF and PIK3CA exon 20 wild type, EGFR GCN ≥ 2.6, HER-3 Rajkumar score ≤ 8, IGF-1 immunostaining < 2) or unfavourable (any of the previous markers altered or mutated). After the introduction of N-RAS status (exons 2, 3, 4) only RAS wild type patients were considered eligible. Results: Forty-six patients were enrolled. Seventeen patients (37%) were allocated to the favourable and 29 patients (63%) to the unfavourable profile. RR in the favourable and unfavourable group was 11/17 (65%) and 2/29 (7%) (p = 0.007) respectively. The favourable group also showed an improved PFS (8months vs. 3months, p < 0.0001) and OS (15months vs. 6months, p < 0.0001). Conclusions: Our results suggest that prospective selection of optimal candidates for cetuximab treatment is feasible and may be able to improve clinical outcom

    Prognostic value for incidental antihypertensive therapy with β-blockers in metastatic colorectal cancer

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    Previous studies suggested that the incidental use of β-blockers might influence clinical outcome in solid tumors. We assessed the correlation between the incidental use of β-blockers and clinical outcome in colorectal cancer patients treated with first-line chemotherapy alone or in combination with bevacizumab in metastatic colorectal cancer patients. We collected data from 235 metastatic colorectal cancer patients treated with first-line chemotherapy alone (128 patients) or with bevacizumab (107 patients). Patients were stratified for clinical factors such as β-blockers use, age, sex, and site of metastases, previous adjuvant chemotherapy and ECOG performance status. In the chemotherapy alone group patients receiving β-blockers showed an improved overall survival (median OS 41.3 vs 25.7 months, P = 0.03, HR: 2.26, 95% CI: 1.05-3.24). A significant relationship with improved response rate was also evident for B-blocker users (P = 0.044). On the contrary in the β-blockers users group treated with chemotherapy in combination with bevacizumab we observed a trend toward a worse overall survival although nonstatistically significant (median OS 18.5 vs 23.6 months, HR: 0. 89, 95% CI: 0.38-2.03, P = 0.77). Our analysis confirmed a potential prognostic role for the use of β-blockers in colorectal cancer patients treated with chemotherapy. Our findings also suggest a potential worse outcome for patients on β-blockers receiving bevacizumab. Future prospective studies should include the incidental use of β-blockers as stratification factor for clinical outcome

    Ultrasonographic assessment of normal jugular veins in Standardbred horses

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    Ultrasonography (US) is the recommended imaging technique to evaluate jugular veins. This prospective randomized clinical study was designed to collect a series of B-mode US measurements of manually distended jugular veins in healthy Italian Standardbreds and to find possible correlations between ultrasound measurements and animal morphometric characteristics. Forty-two horses, eight males and 34 females (range 3-22 years; bodyweight 494.4 ± 41.7 kg), were included in the study. The diameters and wall thicknesses of both jugular veins were measured at three different sites of the neck. The differences in ultrasound measurements based on scans, age, gender, side, and site of the neck were evaluated by ANOVA or by the Kruskal-Wallis test. The effects of the morphometric measures on each ultrasound parameter were evaluated by MANOVA (P < 0.05)

    A theoretical model of neuronal population coding of stimuli with both continuous and discrete dimensions

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    In a recent study the initial rise of the mutual information between the firing rates of N neurons and a set of p discrete stimuli has been analytically evaluated, under the assumption that neurons fire independently of one another to each stimulus and that each conditional distribution of firing rates is gaussian. Yet real stimuli or behavioural correlates are high-dimensional, with both discrete and continuously varying features.Moreover, the gaussian approximation implies negative firing rates, which is biologically implausible. Here, we generalize the analysis to the case where the stimulus or behavioural correlate has both a discrete and a continuous dimension. In the case of large noise we evaluate the mutual information up to the quadratic approximation as a function of population size. Then we consider a more realistic distribution of firing rates, truncated at zero, and we prove that the resulting correction, with respect to the gaussian firing rates, can be expressed simply as a renormalization of the noise parameter. Finally, we demonstrate the effect of averaging the distribution across the discrete dimension, evaluating the mutual information only with respect to the continuously varying correlate.Comment: 20 pages, 10 figure

    Mediastinal Images Resembling Thymus Following 131-I Treatment for Thyroid Cancer

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    The follow-up of Differentiated Thyroid Cancer conventionally includes serum thyroglobulin and periodic Whole Body Scans. The uptake of 131-I in normal and pathological tissues different from metastatic thyroid cancer sites is a cause of false-positive scans. Among them, mediastinal uptake caused by thymic hyperplasia can be observed. The aim of the present study was to review a series of 573 patients with differentiated thyroid cancer treated with 131-I after surgery between 1992 and 2003 looking above all for those with mediastinal images resembling thymus. This evaluation is presented together with some hypotheses on the relationships between thymus and thyroid. Moreover, some considerations are made on the differential diagnosis between thymus and mediastinal tumour thyroid residues

    Loan Officer Authority and Small Business Lending.Evidence from a survey.

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    A vast literature has emphasized that small banks are at a comparative advantage in small business lending. In this paper, we show that apart from size, which is negatively correlated with bank specialization in small business lending, organizational characteristics affect bank loan portfolio choices. By using a unique dataset based on a recent survey of Italian banks, we find that after having controlled for bank size, a branch loan officer’s authority has a key role in explaining bank specialization in small business lending. In particular, banks which delegate more decision-making power to their branch loan officers are more willing to lend to small firms than other banks. We approximate loan officers’ authority by controlling for several factors which shape their incentives: loan officer turnover, the amount of money up to which they are allowed to lend autonomously, their role in loan approval and in setting loan interest rates, the kind of information (soft versus hard information) used for screening and monitoring borrowers, and the structure of their compensation schemes
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