Generation of Noise Time Series with arbitrary Power Spectrum

Noise simulation is a very powerful tool in signal analysis helping to foresee the system performance in real experimental situations. Time series generation is however a hard challenge when a robust model of the noise sources is missing. We present here a simple computational technique which allows the generation of noise samples of fixed length, given a desired power spectrum. A few applications of the method are also discussed.Comment: 4 pages, 7 figure

Management of water distribution systems in PDA conditions using isolation valves: case studies of real networks

Abstract The current paper reports on a case study investigating water distribution system management in emergency conditions when it is necessary to seal off a zone with isolation valves to allow repair. In these conditions, the pressure-driven analysis (PDA) is considered to be the most efficient approach for the analysis of a water distribution network (WDN), as it takes into account whether the head in a node is adequate to ensure service. The topics of this paper are innovative because, until now, previous approaches were based on the analysis of the network behaviour in normal conditions. In emergency conditions, it is possible to measure the reliable functioning of the system by defining an objective function (OF) that helps to choose the optimal number of additional valves in order to obtain adequate system control. The OF takes into account the new network topology by excluding the zone where the broken pipe is located. The results show that the solution did not improve significantly when the number of valves reached a threshold. The procedure applied to other real case studies seems to confirm the efficiency of the methodology even if further examination of other cases in different conditions is necessary

Mimicking the in vivo Environment – The Effect of Crowding on RNA and Biomacromolecular Folding and Activity

In vitro studies on macromolecules, like proteins and nucleic acids, are mostly carried out in highly diluted systems where the molecules are studied under artificial conditions. These experimental conditions are optimized for both the system under investigation and the technique used. However, these conditions often do not reflect the in vivo situation and are therefore inappropriate for a reliable prediction of the native behavior of the molecules and their interactions under in vivo conditions. The intracellular environment is packed with cosolutes (macromolecules, metabolites, etc.) that create 'macromolecular crowding'. The addition of natural or synthetic macromolecules to the sample solution enables crowding to be mimicked. In this surrounding most of the studied biomolecules show a more compact structure, an increased activity, and a decrease of salt requirement for structure formation and function. Herein, we refer to a collection of examples for proteins and nucleic acids and their interactions in crowding environments and present in detail the effect of cosolutes on RNA folding and activity using a group II intron ribozyme as an example

emergency management of water distribution systems the nodal demand control

Abstract During emergency situations (e.g., due to pipe bursts or other network failures), appropriate management of Water Distribution Systems (WDS) is required. Critical events often cause service failures, because the pressure head in some nodes of the network become inadequate to deliver required demand. In this paper, a new methodology is developed based on the nodal demand control. with the aim to increase the pressure head, and hence the flow rate actually delivered at critical nodes (i.e., hospitals, vulnerable customers, etc.). This is done to avoid or minimize service interruptions between the failure and the repair times. Furthermore, a pipe burst can cause isolation of a portion of the network such that the flow along pipes changes and this causes the reduction of head in some nodes. The proposed methodology is manages the delivered flow rate using a Pressure Driven Analysis (PDA) approach. This is based on operating control of valves and by identifying the nodes where the pressure control should be implemented. Those control nodes are chosen by the analysis of sensitivity matrices and the Max-Sum Method (Bush and Uber, 1998; Fiorini Morosini et al., 2014). The methodology is demonstrated on a case study for a real network of Cosenza, a town in the South of Italy

A Simple Reactive Obstacle Avoidance Algorithm and Its Application in Singapore Harbor

Autonomous surface craft (ASC) are increasingly attractive as a means for performing harbor operations including monitoring and inspection. However, due to the presence of many fixed and moving structures such as pilings, moorings, and vessels, harbor environments are extremely dynamic and cluttered. In order to move autonomously in such conditions ASC’s must be capable of detecting stationary and moving objects and plan their paths accordingly. We propose a simple and scalable online navigation scheme, wherein the relative motion of surrounding obstacles is estimated by the ASC, and the motion plan is modified accordingly at each time step. Since the approach is model-free and its decisions are made at a high frequency, the system is able to deal with highly dynamic scenarios. We deployed ASC’s in the Selat Pauh region of Singapore Harbor to test the technique using a short-range 2-D laser sensor; detection in the rough waters we encountered was quite poor. Nonetheless, the ASC’s were able to avoid both stationary as well as mobile obstacles, the motions of which were unknown a priori. The successful demonstration of obstacle avoidance in the field validates our fast online approach.Massachusetts Institute of Technology. Singapore-MIT Alliance in Research and Technology (SMART

Tobacco exposure and complications in conservative laryngeal surgery.

Smoking is an important risk factor in the development of head and neck cancer. However, little is known about its effects on postoperative complications in head and neck cancer surgery. We performed a retrospective analysis on 535 consecutive laryngeal cancer patients submitted to open partial laryngectomy at the Otolaryngology-Head and Neck Surgery Department of Florence University to evaluate a possible correlation between smoking and surgical complications. Patients were grouped in non smokers and smokers and evaluated for airway, swallowing, local and fistula complications by multivariate analysis: 507 (95\%) patients were smokers, 69\% presented supraglottic, 30\% glottic and 1\% transglottic cancer. The most common operation was supraglottic horizontal laryngectomy in 58\%, followed by supracricoid partial laryngectomy in 27\% and frontolateral hemilaryngectomy in 15\% of cases. The incidence of overall complications was 30\%, airway complications representing the most frequent (14\%), followed by swallowing (7\%), local (6\%) and fistula complications (3\%). Smokers developed more local complications (p = 0.05, univariate, p = 0.04, multivariate analysis) and pharyngocutaneous fistula (p = 0.01, univariate, p = 0.03, multivariate analysis)

Subtotal supracricoid laryngectomy: changing in indications, surgical techniques and use of new surgical devices.

The aim of this study is to evaluate the evolution of supracricoid partial laryngectomy (SCPL) in indications, surgical techniques and outcomes through last decades.A retrospective analysis of 146 patients affected by laryngeal cancer treated with SCPL was carried on. We defined: (1) group A, 100 patients treated by cold instruments between 1995 and 2004; (2) group B, 46 patients treated by harmonic scalpel between 2005 and 2010. Complications rate, and functional and oncological results were documented and a comparison between the two groups was made; histopathological analysis of surgical margins was evaluated and correlated with local incidence of recurrence.Significant differences in age mean-value (p=0.02), T classification (p=0.007), and in indication for more advanced-staged patients were found in group B (p=0.001). Surgical procedure was shorter in group B (p<0.001), with shorter swallowing recovery (p=0.003). Oncological outcomes did not report any significant differences. Group B showed a higher incidence of post- operative arytenoid edema (p=0.03) associated with a lower rate of pneumonia (p=0.038). Despite a higher rate of close or positive-margins found in group B no higher incidence of local-recurrence was reported (p=0.02) compared to group A.We documented changing in indications and surgical technique for SCPL because of the development of modern diagnostic techniques and the introduction of low-thermal injury device allowing a more challenging tumor excision as well as with a shorter swallowing recovery in our series

Is open tracheotomy performed by residents in otorhinolaryngology a safe procedure? a retrospective cohort study.

Surgical or percutaneous tracheotomy is one of the commonest operations in the ENT practice and one of the first procedures to be taught to residents. No study exists that demonstrates the safety of this surgical procedure performed by unexperienced surgeons. The purpose was to compare outcomes of tracheotomies performed by supervised residents and surgeons in terms of postoperative complications and mortality, and identify risk factors for the onset of complications. Retrospective cohort study. Otolaryngology-Head and Neck Surgery Department, University of Florence, Italy. We included all patients undergoing tracheotomy from July 2008 to January 2013 and compared tracheotomies performed by supervised residents or surgeons. During the study period, 304 patients were submitted to tracheotomy. Patients operated by surgeons had a significantly higher number of tracheal rings fracture (p = 0.05), subcutaneous emphysema (p = 0.003) and tracheostomy tube displacement (p = 0.003), while supervised residents had a higher number of tracheitis/pneumonia (p = 0.04) as early complications. Patients operated by supervised residents had a significantly higher number of tube obstructions as late complication (p = 0.04). Using multivariate model, risk factors for early postoperative complications were male sex (p = 0.04) and delayed time to substitution with cuffless tube (p = 0.01), while only a trend to statistical significance was observed for urgent tracheotomies concerning the risk for late postoperative complications (p = 0.08). The current practice where residents perform tracheotomies supervised by a surgeon should not be disheartened. Our study demonstrates that it is safe and does not lead to higher risk of complications nor negatively affects the quality of care