Diffusion Model of a Non-Integer Order PIγ Controller with TCP/UDP Streams.

In this article, a way to employ the diffusion approximation to model interplay between TCP and UDP flows is presented. In order to control traffic congestion, an environment of IP routers applying AQM (Active Queue Management) algorithms has been introduced. Furthermore, the impact of the fractional controller PIγ and its parameters on the transport protocols is investigated. The controller has been elaborated in accordance with the control theory. The TCP and UDP flows are transmitted simultaneously and are mutually independent. Only the TCP is controlled by the AQM algorithm. Our diffusion model allows a single TCP or UDP flow to start or end at any time, which distinguishes it from those previously described in the literature.

Late-onset bloodstream infections of Very-Low-Birth-Weight infants: data from the Polish Neonatology Surveillance Network in 2009-2011.

BACKGROUND: Late-Onset Bloodstream Infections (LO-BSI) continue to be one of the most important complications associated with hospitalization of infants born with very low birth weight (VLBW). The aims of this study were to assess the epidemiology of LO-BSI together with the risk factors and the distribution of causative pathogens at six Polish neonatal intensive care units that participated in the Polish Neonatology Surveillance Network from January 1, 2009 to December 31, 2011. METHODS: The surveillance covered 1,695 infants whose birth weights were <1501 grams (VLBW) in whom LO-BSI was diagnosed >72 hours after delivery. Case LO-BSI patients were defined according to NeoKISS. RESULTS: Four hundred twenty seven episodes of LO-BSI were diagnosed with a frequency of 25.3% and an incidence density of 6.7/1000 patient-days (pds). Results of our multivariate analysis demonstrated that surgical procedures and lower gestational age were significantly associated with the risk of LO-BSI. Intravascular catheters were used in infants with LO-BSI significantly more frequently and/or for longer duration: Central venous cathters (CVC) (OR 1.29) and Peripheral venous catheters (PVC) (OR 2.8), as well as, the total duration of total parenteral nutrition (13 vs. 29 days; OR 1.81). Occurrence of LO-BSI was significantly associated with increased the length of mechanical ventilation (MV) (OR 2.65) or the continuous positive airway pressure (CPAP) (OR 2.51), as well as, the duration of antibiotic use (OR 2.98). The occurrence of more than one infection was observed frequently (OR 9.2) with VLBW with LO-BSI. Microorganisms isolated in infants with LO-BSI were dominated by Gram-positive cocci, and predominantly by coagulase-negative staphylococci (62.5%). CONCLUSIONS: Independent risk factor for LO-BSI in VLBV infants are: low gestational age and requirement for surgery. The incidence rates of LO-BSI especially CVC-BSI were higher in the Polish NICUs surveillance than those of other national networks, similar to the central- and peripheral utilization ratio.

Local controllability and optimal control for a model of combined anticancer therapy with control delays.

We study some control properties of a class of two-compartmental models of response to anticancer treatment which combines anti-angiogenic and cytotoxic drugs and take into account multiple control delays. We formulate sufficient local controllability conditions for semilinear systems resulting from these models. The control delays are related to PK/PD effects and some clinical recommendations, e.g., normalization of the vascular network. The optimized protocols of the combined therapy for the model, considered as solutions to an optimal control problem with delays in control, are found using necessary conditions of optimality and numerical computations. Our numerical approach uses dicretization and nonlinear programming methods as well as the direct optimization of switching times. The structural sensitivity of the considered control properties and optimal solutions is also discussed.

Infections reported in newborns with very low birth weight who required surgical treatment. Data from the Polish Neonatology Surveillance Network.

AIM: To determine the risk of various forms of infections appearing in very low birth weight newborns (VLBW) during the period of 30 days after surgical treatment in hospitals which have perinatal care departments with neonatal intensive care units that form the Polish Neonatology Surveillance Network (PNSN). MATERIAL AND METHODS: Continuous prospective monitoring of infections was carried out from January 1st to December 31st 2009 in six neonatal intensive care units which form the Polish Neonatal Surveillance Network. (PNSN). 910 newborns with very low birth weight (VLBW) were included in the study programme. 91 (10%) of this group underwent 118 surgical interventions. 12 newborns needed two or more surgeries. The most common procedure was the closure of persistent ductus artesiosus (PDA) and photocoagulation of vascular damage in the eye fundus. RESULTS: In the period of 30 days after surgery the following were diagnosed: in 3 newborns - necrotizing enterocolitis (NEC), in 22 newborns - sepsis (BSI) and in 54 newborns - pneumonia (PNEU). Symptoms of BSI and PNEU were on average observed on the 10th day after surgical intervention, while in the case of NEC on the 17th day. The highest incidence of infection (148.4%) was observed after PDA closure and in connection with introducing a drain into the pleural cavity through the intercostal space. The incidence of PN EU (37.3%) was twice as high as the incidence of BSI (18.6%). Surgical procedure was a factor significantly increasing the risk of infection and morbidity (RR 2.1, P<001) In our investigations there was no case of the local infection of a surgical site. 11 newborns died (mortality was 12.1%). The most common bacterial strains found in our investigation were coagulase-negative Staphylococcus and Escherichia Coli. CONCLUSIONS: Taking into consideration the fact that surgical procedure in VLBW-newborns significantly increases the risk of pneumonia and to a minor degree the risk of NEC and BSI, further detailed investigation in the field of perisurgical epidemiology is needed in order to elaborate a more deeply oriented and more effective strategy of infection prevention in the group of VLBW newborns.

[Epidemiology of infections in very low birth weight infants. Polish Neonatology Network research]. / Epidemiologia Zakazen Noworodkówz Bardzo Mala Masa Urodzeniowa.badania Polskiej Sieci Neonatologicznej.

AIM OF STUDY: 1. prospective record of infections; 2. prevention of nosocomial infections by providing current data about infections, which are significant for making therapeutic decisions. MATERIAL AND METHODS: Recorded infections: early-onset sepsis (congenital), late-onset sepsis (acquired in hospital), necrotising enterocolitis (NEC), pneumonia. Infections were diagnosed and qualified on the basis of definitions of infections based on the National Nosocomial Infections Surveillance (NNIS) criteria, developed by CDC, USA, including modifications of German Neo-KISS programme. Infection control was realised as a part of common research project of "Polish Neonatology Network", appointed by the decision of the Minister of Science and Higher Education no. 669/E-215/BWSN- 0180/2008 dated 20.05.2008 r. The study was conducted by 6 Polish neonatology units, Microbiology Chair of Jagiellonian University Collegium Medicum and Institute of Theoretical and Applied Computer Science. Infants with birth weight lower than 1500 g were qualified for the study. RESULTS: Between 1.01.2009 and 31.12.2009, 910 patients were registered, i.e. 19.1% of VLBW infants born in that period. The conducted analysis showed significant differences between centres in gestational age, birth weight, hospitalisation, use of invasive procedures, antibiotics and parenteral feeding. Cumulative morbidity rate was 68.5% total. Blood infection (sepsis) was the most commonly observed type of infection: 268 cases - 43.1% of all recorded forms of infection. Pneumonia was diagnosed in 242 cases, 38.8% total. NEC constituted 12.7% studied infections (79 cases). Apart from NEC, the risk of other forms of infection differed between centres. Dominant etiologic factor of all infections were Gram-positive cocci, which constituted 565 isolated microorganisms. Among them coagulase-negative staphylococci (CNS) were the most common (41.7%), while Staphylococcus aureus was fourth most frequent etiologic factor of infections (6.3% total). CONCLUSIONS: 1. Introduction of unified definition and criteria for diagnosing infections and the use of morbidity rates enables comparative analysis of epidemiology of infections in neonatal intensive care units. 2. Due to significant differences observed between prophylactic and therapeutic procedures in various units, it is essential to propose Polish recommendations regarding control over etiology of infections and use of invasive procedures, such as intravenous catheters and ventilation. 3. It is essential to undertake action leading to fully rational antibiotic therapy, because overuse of antibiotics leads to bacterial resistance and increases incidence of infections.

Early-onset infections of very-low-birth-weight infants in Polish neonatal intensive care units.

AIM: The objective of this study was to investigate the incidence, causes, the risk factors, etiologic agents and the outcomes of early-onset infections (EOIs) in very-low-birth-weight newborns in Polish neonatal intensive care units. METHODS: Continuous prospective infection surveillance conducted during 2009 at 6 Polish neonatal intensive care units and included 910 newborns whose birth weight was lower than 1500 g. Infections were defined according to the Gastmeier's criteria. EOIs were diagnosed <3 days after delivery. RESULTS: The frequency of early-onset septicemia (EOS) was 7.0% and of early-onset pneumonia (EO-pneumonia) 8.6%. The factors significantly increasing the risk of EOS were low gestational age, small birth weight, low score in the Clinical Risk Index for Babies and Apgar score as well as maternal chorioamnionitis. The perinatal prophylaxis did not have an influence on the occurrence of EOS. The factors considerably increasing the risk of EO-pneumonia were low scores in the Clinical Risk Index for Babies and Apgar scores, a low gestational age and bacterial vaginosis in the child's mother during pregnancy. The most important etiologic organisms were Gram-positive cocci (39.7% of all the infections, 47.8% in EOS), Streptococcus agalactiae (20% of the EOS), Gram-negative bacilli (33.3% isolates), yeast-like fungi (isolated in 7.9% of cases) and atypical bacteria (22% of the cases of EO-pneumonia). CONCLUSIONS: The observed frequency of EOS did not differ from the one described in the literature, whereas the frequency of EO-pneumonia was higher. The bacterial etiologies suggest the vertical transmission of the pathogens and a close relationship between the observed EOIs with maternal environment. The applied perinatal antibiotic prophylaxis was ineffective.