Universal hierarchical behavior of citation networks

Many of the essential features of the evolution of scientific research are imprinted in the structure of citation networks. Connections in these networks imply information about the transfer of knowledge among papers, or, in other words, edges describe the impact of papers on other publications. This inherent meaning of the edges implies that citation networks can exhibit hierarchical features that are typical of networks based on decision making. In this paper, we investigate the hierarchical structure of citation networks consisting of papers in the same field. We find that the majority of the networks follow a universal trend towards a highly hierarchical state, and the various fields display differences only concerning (i)their phase in life (distance from the 'birth' of a field) or (ii)the characteristic time according to which they are approaching the stationary state. We also show by a simple argument that the alterations in the behavior are related to and can be understood by the degree of specialization corresponding to the fields. Our results suggest that during the accumulation of knowledge in a given field, some papers are gradually becoming relatively more influential than most other papers. © 2014 IOP Publishing Ltd and SISSA Medialab srl

Application of Wavelet Packet Transform and Envelope Analysis to Non-stationary Vibration Signals For Fault Diagnosis of a Reciprocating Compressor

Reciprocating compressors play a major role in manufacturing industries such as oil and gas refineries, petrochemical industrial plants, etc. Therefore, it is necessary to implement online condition monitoring for early and accurate detection of faults which if not controlled can lead to machine inefficiency, damage, or total system shutdown. This paper presents the application of wavelet packet transform (WPT) and envelope analysis to non-stationary vibration signal from a two-stage reciprocating compressor for fault diagnostics. Vibration signal measured on the reciprocating compressor consist of a series of impulsive events with non-stationary random characteristics, which result mostly from mechanical impacts of the valves and impulsive fluid excitation of high-pressure turbulent flows. To characterize such vibration signal, WPT is employed to decompose the measured signal for the extraction of time-frequency information. With the help of statistical based analysis, the most optimal terminal node of the wavelet packet is selected for further study. Envelope spectrum of the optimal terminal node is processed and used for the classification of three common faults including intercooler leakage, second-stage discharge valve leakage and a combined fault at five critical tank discharge ranges (0.55, 0.62, 0.69, 0.76, and 0.83 MPa) for condition monitoring of a reciprocating compressor

Comparative Experiment on the Use of Unmanned and Ground-Based Technologies of Fertilizer and Crop Protection Products on Winter Barley

The results of a comparative experiment of the use of an agricultural drone Agras T10 and ground agricultural machines (Amazone ZA-X Perfect fertilizer spreader, Amazone UF-901 sprayer) for the application of nitrogen fertilizers and plant protection products (herbicides, insecticides and fungicides treatment) are presented. Yield of experimental and control plots, economic efficiency of unmanned and ground technologies are determined. Calculation of economic efficiency of unmanned technology showed that its productivity is 4 times less. While using this technology with differentiated fertilizer application the winter barley yield increased by 3,6% while the amount of fertilizer application decreased by 2%. Consumption of fuel and lubricants decreased by 1.4 times, metal consumption by 26.7 times

Effect of correlations on network controllability

A dynamical system is controllable if by imposing appropriate external signals on a subset of its nodes, it can be driven from any initial state to any desired state in finite time. Here we study the impact of various network characteristics on the minimal number of driver nodes required to control a network. We find that clustering and modularity have no discernible impact, but the symmetries of the underlying matching problem can produce linear, quadratic or no dependence on degree correlation coefficients, depending on the nature of the underlying correlations. The results are supported by numerical simulations and help narrow the observed gap between the predicted and the observed number of driver nodes in real networks

Large random correlations in individual mean field spin glass samples

We argue that complex systems must possess long range correlations and illustrate this idea on the example of the mean field spin glass model. Defined on the complete graph, this model has no genuine concept of distance, but the long range character of correlations is translated into a broad distribution of the spin-spin correlation coefficients for almost all realizations of the random couplings. When we sample the whole phase space we find that this distribution is so broad indeed that at low temperatures it essentially becomes uniform, with all possible correlation values appearing with the same probability. The distribution of correlations inside a single phase space valley is also studied and found to be much narrower.Comment: Added a few references and a comment phras

Radioluminescence results from an Al2O3:C fiber prototype: 6 MV medical beam

The Investigations of this article focus on the response of an Al2O3:C radioluminescence (RL) prototype for medical dosimetry in a 6 MV photon beam. The prototype can be configured using two types of detectors coupled to fiber-optic cables - single crystal (1 x 1 x 2 mm(3)) and droplets (in two grain sizes, 38 and 4 mu m, molded in r =0.5 mm,1= 200 mu m). By using the appropriate filters in addition to time gating it is possible to remove disturbance present during irradiation: the stem effect. Pre -irradiation of the dosimeters to a dose of 300 Gy made the memory effects in Al2O3:C negligible, so as to not impair the dosimetric properties of the system. The key findings are that the system is suitable for small field beam dosimetry, while giving overall good dose response in other features (i.e., beam profile, dose rate - FF and FFF modes). The results show that our prototype can be used for real time dose rate assessment in medical photon dosimetry without many correction factors. The 41 mu m RL measurement results are in excellent agreement (i.e. below 1%) with the dose delivered according to standard beam data

Individualized Stabilization Criteria–Driven Ranibizumab versus Laser in Branch Retinal Vein Occlusion

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Individualized Ranibizumab Regimen Driven by Stabilization Criteria for Central Retinal Vein Occlusion

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Metabolic Syndrome and Cardiovascular Risk Factors in Obese Adolescent

BACKGROUND: Childhood and adolescent obesity is associated with insulin resistance, abnormal glucose metabolism, hypertension, dyslipidemia, inflammation, liver disease, and compromised vascular function. The purpose of this study was to determine the prevalence of cardiovascular risk factor abnormalities and metabolic syndrome in a sample of obese adolescent as prevalence data might be helpful in improving engagement with obesity treatment in future. The high blood lipid levels and obesity are the main risk factors for cardio vascular diseases. Atherosclerotic process begins in childhood.AIM: This study aimed to investigate the relationship between obesity in adolescent and their blood lipids levels and blood glucose level.METHODS: This study was conducted with 100 adolescents of both gender age 12-17 years and body mass index (BMI) greater than 95th percentiles and 100 normal adolescents as control group. The blood samples were collected from all adolescents after overnight fasting (10 hours) to analyze blood lipids (Total cholesterol, high density lipoprotein, low density lipoprotein) and hematological profile (Hemoglobin, platelets and red blood cell, C reactive protein and fasting blood glucose.RESULTS: There were statistical difference between the two groups for red blood cells (P<0.001), Hemoglobin (P < 0.001) and platelets (P = 0.002), CRP (P = 0.02). Positive correlation was found between the two groups as regards total cholesterol (P = 0.0001), P value was positive for HDL (P = 0.005 and Atherogenic index P value was positive (P = 0.002). Positive correlation was found between the two group as regards fasting blood glucose (P = 0.001).CONCLUSION:  Saturated fat was associated with elevated lipid levels in obese children. These results reinforce the importance of healthy dietary habits since child-hood in order to reduce the risks of cardiovascular diseases in adulthood

Infrared luminescence for real time ionizing radiation detection

Radio-luminescence (RL) optical fiber sensors enable a remote, punctual, and real time detection of ionizing radiation. However, the employment of such systems for monitoring extended radiation fields with energies above the Cerenkov threshold is still challenging, since a spurious luminescence, namely, the "stem effect," is also generated in the passive fiber portion exposed to radiation. Here, we present experimental measurements on Yb-doped silica optical fibers irradiated with photon fields of different energies and sizes. The results demonstrate that the RL of Yb3+, displaying a sharp emission line at about 975 nm, is free from any spectral superposition with the spurious luminescence. This aspect, in addition with the suitable linearity, reproducibility, and sensitivity properties of the Yb-doped fibers, paves the way to their use in applications where an efficient stem effect removal is required