Power Allocation and Time-Domain Artificial Noise Design for Wiretap OFDM with Discrete Inputs

Optimal power allocation for orthogonal frequency division multiplexing (OFDM) wiretap channels with Gaussian channel inputs has already been studied in some previous works from an information theoretical viewpoint. However, these results are not sufficient for practical system design. One reason is that discrete channel inputs, such as quadrature amplitude modulation (QAM) signals, instead of Gaussian channel inputs, are deployed in current practical wireless systems to maintain moderate peak transmission power and receiver complexity. In this paper, we investigate the power allocation and artificial noise design for OFDM wiretap channels with discrete channel inputs. We first prove that the secrecy rate function for discrete channel inputs is nonconcave with respect to the transmission power. To resolve the corresponding nonconvex secrecy rate maximization problem, we develop a low-complexity power allocation algorithm, which yields a duality gap diminishing in the order of O(1/\sqrt{N}), where N is the number of subcarriers of OFDM. We then show that independent frequency-domain artificial noise cannot improve the secrecy rate of single-antenna wiretap channels. Towards this end, we propose a novel time-domain artificial noise design which exploits temporal degrees of freedom provided by the cyclic prefix of OFDM systems {to jam the eavesdropper and boost the secrecy rate even with a single antenna at the transmitter}. Numerical results are provided to illustrate the performance of the proposed design schemes.Comment: 12 pages, 7 figures, accepted by IEEE Transactions on Wireless Communications, Jan. 201

The Effects of Survival Predictors Before Hemodialysis Initiation is Different in Adults and the Elderly

SummaryBackgroundThe aim of this study is to investigate the effects of the risk markers of sex, education, marital status, nephrology referral, and progression of comorbid conditions before hemodialysis (HD) on the survival of incident HD patients in different age groups.MethodsA total of 7729 incident HD patients were recruited in this retrospective cohort study in 2006 and followed up to the end of 2007. Patients were divided according to their age, being classified as Adult (18–64 years), Young Elderly (65–74 years), or Old Elderly ≥ 75 years. The progressive Romano-Charlson Comorbidity Index (CCIp) was used to predict survival outcomes, CCIp = CCI−1–CCI−3, where CCI−1 and CCI−3 are the CCI scores in the 1st year and 3rd year before HD initiation, respectively. The Cox regression model was used to analyze the associated factors of survival.ResultsMale patients were found to have a higher risk of mortality than females in each age group. Education ≤ 6 years was an independent risk marker for mortality in the Adult group. The effect of marital status and early nephrology referral on survival was more significant in the elderly groups. The CCIp and CCI-3 ≥ 3 were independent risk markers for mortality in each group. The CCIp was a more valuable predictor of survival in adults than in elderly HD patients.ConclusionThe effects of sex, education, marital status, early nephrology referral, and severity of CCI-3 and CCIp before HD initiation on patient survival vary in different age groups

Acute Fatty Liver of Pregnancy in a Taiwanese Tertiary Care Center: A Retrospective Review

SummaryObjectiveTo evaluate the demographics, clinical presentations, laboratory findings, and maternal and fetal outcomes in patients with acute fatty liver of pregnancy.Materials and MethodsA retrospective review was conducted of the records of pregnant patients with a diagnosis of acute fatty liver in a tertiary medical center over a 22-year period.ResultsEighteen patients with acute fatty liver of pregnancy were recruited, all of whom developed the disease in the third trimester. Eleven women (61%) were primigravid and four (22%) had twin pregnancies; six (33%) were diagnosed antepartum, and the other 12 (67%) were diagnosed postpartum. There were two maternal deaths (11%) and four fetal deaths (18%). The most common complications apart from severe liver dysfunction were acute renal failure (83%), hypoglycemia (61%), and disseminated intravascular coagulation (61%).ConclusionWomen who become acutely ill during the third trimester of pregnancy should undergo tests for acute fatty liver of pregnancy, including laboratory tests for assessing liver function and coagulation profile

Artificial Intelligence and Visual Analytics: A Deep-Learning Approach to Analyze Hotel Reviews & Responses

With a growing number of online reviews, consumers often rely on these reviews to make purchase decisions. However, little is known about managerial responses to online hotel reviews. This paper reports on a framework to integrate visual analytics and machine learning techniques to investigate whether hotel managers respond to positive and negative reviews differently and how to use a deep-learning approach to prioritize responses. In this study, forty 4- and 5-star hotels in London with 91,051 reviews and 70,397 responses were collected and analyzed. Visual analyses and machine learning were conducted. The results indicate most hotels (72.5%) showing no preference to respond to positive and negative reviews. Our proposed deep-learning approach outperformed existing algorithms to prioritize responses

Ontology-based Fuzzy Markup Language Agent for Student and Robot Co-Learning

An intelligent robot agent based on domain ontology, machine learning mechanism, and Fuzzy Markup Language (FML) for students and robot co-learning is presented in this paper. The machine-human co-learning model is established to help various students learn the mathematical concepts based on their learning ability and performance. Meanwhile, the robot acts as a teacher's assistant to co-learn with children in the class. The FML-based knowledge base and rule base are embedded in the robot so that the teachers can get feedback from the robot on whether students make progress or not. Next, we inferred students' learning performance based on learning content's difficulty and students' ability, concentration level, as well as teamwork sprit in the class. Experimental results show that learning with the robot is helpful for disadvantaged and below-basic children. Moreover, the accuracy of the intelligent FML-based agent for student learning is increased after machine learning mechanism.Comment: This paper is submitted to IEEE WCCI 2018 Conference for revie

Electroencephalography and transcranial Doppler ultrasonography in neonatal citrullinemia

The authors present a case of citrullinemia with a genotype of argininosuccinate synthetase (ASS1), c.380 G>A (p.R127Q)/c.380 G>A (p.R127Q), in two alleles. A 3-day-old female infant presented with status epilepticus and coma. Laboratory data showed hyperammonemia and marked lactic acidosis in the blood and cerebrospinal fluid; electroencephalography showed severely suppressed cerebral activity and focal paroxysmal volleys of slow and sharp waves (< 1Hz) over the left hemisphere. Real-time transcranial Doppler ultrasonography showed a brain edema and high peaked systolic and low diastolic flows in basal, anterior, and middle cerebral arteries; however, immediately after a blood exchange transfusion, systolic flows were lower and diastolic flows were higher. The resistance indices were significantly different (means: 0.58 vs. 0.37; p=0.01). The patient was placed on diet therapy. After six blood exchange transfusions and peritoneal dialysis, her neurologic examination results and serum ammonia and lactate values were normal. The authors found that electroencephalography and transcranial Doppler ultrasonography were useful for the diagnosis and follow-up treatment of neonatal citrullinemia

AN ELECTROMAGNETIC ACTUATOR IN LAB-ON-A-CHIP SYSTEMS

ABSTRACT A novel technique for the fabrication of electromagnetic micro actuators was proposed and a prototype was designed and fabricated in this study. The constituent parts of the designed actuator are comprised of the diaphragm, the micro coils, and the magnet. When an electrical current was applied to the micro coils, the magnetic force between the magnet and the coil is produced, causes the diaphragm to deflect and becomes the source of actuation. The fabrication process of the actuator combines Optical Lithography, Electron Beam Evaporation, and Electroplating. The structure of the actuating device uses PDMS as the vibrating diaphragm and electroplated copper as the coils. The diaphragm deflection can be regulated by varying the electrical current passed through the micro coil and hence the actuating effects can be controlled. The experimental results show that the maximum diaphragm deflection within elastic limits is 150 m at an electrical current of 0.6 A for a micro coil of 100 m line width. The micro electromagnetic actuator proposed in this study is easily fabricated and is readily integrated with Lab-on-a-Chip systems due to its planar structure

Degradation of phenolic compounds in water by non-thermal plasma treatment

A stainless-steel hollow needle type anode was used in the reactor to treat industrial wastewater by gas-liquid phase non-thermal plasma by corona discharge. The results showed that the short electrode gap, 1 cm, has a higher plasma energy density which improves the removal of the phenolic derivatives, reaching 100% after about 60 min. The H₂O₂ concentration was higher in the discharge system when the content of oxygen was increased. The efficiency of the phenol removal by chemical oxygen demand was only 10 – 31% after 60 minutes. The identifie dinterme diates were catechol, hydroquinone,1,4-benzoquinone, 2-nitrophenol,1,2-benzenedicarboxylic acid, diphenylmethanone, 2-methyl-hydroquinone, 2-methyl-1,4-bezoquinone, and trace amounts of organic