1,720,984 research outputs found
Replica symmetric evaluation of the information transfer in a two-layer network in presence of continuous and discrete stimuli
No full textIn a previous paper we have evaluated analytically the mutual information between the firing rates of N independent units and a set of multidimensional continuous and discrete stimuli, for a finite population size and in the limit of large noise. Here, we extend the analysis to the case of two interconnected populations, where input units activate output ones via Gaussian weights and a threshold linear transfer function. We evaluate the information carried by a population of M output units, again about continuous and discrete correlates. The mutual information is evaluated solving saddle-point equations under the assumption of replica symmetry, a method that, by taking into account only the term linear in N of the input information, is equivalent to assuming the noise to be large. Within this limitation, we analyze the dependence of the information on the ratio M/N, on the selectivity of the input units and on the level of the output noise. We show analytically, and confirm numerically, that in the limit of a linear transfer function and of a small ratio between output and input noise, the output information approaches asymptotically the information carried in input. Finally, we show that the information loss in output does not depend much on the structure of the stimulus, whether purely continuous, purely discrete or mixed, but only on the position of the threshold nonlinearity, and on the ratio between input and output noise
Theoretical model of neuronal population coding of stimuli with both continuous and discrete dimensions
No full textIn 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
Response to repeat echoendoscopic celiac plexus neurolysis in pancreatic cancer patients: A machine learning approach
No full textComparison between fine-needle biopsy and fine-needle aspiration for EUS-guided sampling of subepithelial lesions: a meta-analysis
No full textLong-term liver stiffness assessment in hepatitis C virus patients undergoing antiviral therapy: Results from a 5-year cohort study
No full textBACKGROUND AND AIM:
Observational studies showed significant liver stiffness regression after sustained virological response, but long-term effects of antiviral therapy are still unknown. The aim of this study was to assess the magnitude of change in stiffness up to 5 years after therapy in hepatitis C patients undergoing antiviral treatment.
METHODS:
Data of 153 patients were retrieved. Stiffness was assessed by Fibroscan at baseline, end of treatment, 6 months after treatment, and every year hereafter up to 5 years.
RESULTS:
Seventy patients were treated with interferon-based regimens and 83 with direct antiviral agents. Baseline cirrhosis was diagnosed in 53 (34.6%) patients. Sustained virological response was achieved in 112 patients, whereas 41 were non-responders. In responders, stiffness decreased from 12.3 kPa (9-17.8) to 6.6 kPa (5.3-7.4) at 5 years. A sharper decline was observed immediately after treatment (-2.5 kPa at the end of treatment and -3.7 kPa at 6 months), while from 1 year onwards, the magnitude of stiffness decrease was progressively lower. In non-responders, stiffness showed a slight decrease at the end of treatment (from 19.2 to 18.1 kPa), then returned to baseline levels at 6 months (19.4 kPa), and finally increased over time up to 23.7 kPa (15-32.5) at 5 years. The proportion of cirrhotic patients decreased by 50% at 6 months and finally fell < 5% at 4 years after treatment.
CONCLUSIONS:
Stiffness declines significantly after achieving response, and the magnitude of decline is greater in the first year after treatment, while it tends to plateau from 1 year onwards
Diagnostic yield of Franseen and Fork-Tip biopsy needles for endoscopic ultrasound-guided tissue acquisition: a meta-analysis
No full textDiagnostic yield of EUS-guided through-the-needle biopsy in pancreatic cysts: a meta-analysis
No full textCirrhosis Is a Predictor of Adverse Events in Endoscopic Ultrasound Fine-Needle Aspiration: A Propensity-Score Analysis
No full textFull-spectrum versus standard colonoscopy for improving polyp detection rate: A systematic review and meta-analysis
No full textBACKGROUND AND AIM:
Full-spectrum endoscopy represents a new endoscopic platform allowing a panoramic 330 degree view of the colon, but evidence of its superiority over standard colonoscopy is still lacking. Our study is the first meta-analysis comparing the efficacy of full-spectrum endoscopy with standard colonoscopy.
METHODS:
Through a systematic literature review until May 2017, we identified eight randomized-controlled trials. Primary outcomes were polyp detection rate and adenoma detection rate, while cecal intubation time and total colonoscopy time were secondary outcomes. Direct meta-analysis was performed using a random effects model.
RESULTS:
No difference in terms of polyp detection rate and adenoma detection rate was found (risk ratio: 1.00, 95% confidence interval 0.89-1.12, P = 0.96, and 1.05, 0.94-1.17, P = 0.40, respectively). Adenoma miss rate resulted significantly in favor of full-spectrum endoscopy (risk ratio: 0.35, 0.25-0.48, P < 0.01), although the difference was not significant for greater (>5 mm) and pedunculated lesions (risk ratio: 0.38, 0.09-1.60, P = 0.19, and risk ratio: 0.15, 0.01-3.00, P = 0.21, respectively). Cecal intubation time was not different between the two techniques (mean standardized difference: 0.22 min, -1.18 to 1.62, P = 0.76), while total colonoscopy time was significantly shorter when adopting full-spectrum endoscopy (mean difference: -2.60, -4.60 to -0.61, P = 0.01). Sensitivity analysis confirmed all the findings.
CONCLUSIONS:
Full-spectrum endoscopy appears as a promising and reliable technology able to significantly decrease the number of adenomas missed and procedural times, while its superiority over standard colonoscopy in terms of adenoma detection rate results is still unclear
Breastfeeding with and without the WHO/UNICEF baby-friendly hospital initiative: A cross-sectional survey
No full textThe World Health Organization and United Nations Children's Fund's Baby-Friendly Hospital Initiative is aimed at the global promotion, protection and support of breastfeeding. In this study, we compared breastfeeding-related information received, knowledge and behaviours among postpartum women in Baby-Friendly Hospital Initiative accredited and non-accredited hospitals. We selected 10 hospitals: 9 non-accredited hospitals in the Campania region in southern Italy and one accredited hospital in the Piedmont region in northern Italy. In total, 786 women (580 (73.8%) in Campania and 206 (26.2%) in Piedmont) in the hospitals' maternity wards completed a questionnaire comprising 5 sections within 24 to 72hours after giving birth. The questionnaire investigated breastfeeding activities in the days immediately following childbirth, as well as the information provided by health personnel, knowledge about breastfeeding before and during hospitalisation, and participation in antenatal classes. To evaluate the comparison between the 2 regions, we performed at first a bivariate analysis and then a multinomial and a multivariate logistic regression. Compared with Piedmont, in Campania hospitals there was a rate of breastfeeding of 44.3% vs 89.3%, a skin-to-skin contact between mother and child of 74.5% vs 90.7% and first milk feed within 2hours of 15.0% vs 87.2%. The Campania group had fewer problems with child latching. The Campania group reported receiving less information about breastfeeding in general compared with the Piedmont group. In general, both groups showed good basic knowledge about different aspects of breastfeeding. In both regions, about 90% reported that the information received during the antenatal classes simplified the breastfeeding experience. Our study confirms the importance of systematic promotion of breastfeeding and subsequent delivery of adequate support to maternity departments, in accordance with international guidelines
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