Collision-free prioritized medium access in the presence of hidden nodes without relying on out-of-band signaling

Consider the problem of sharing a wireless channel between a set of computer nodes. Hidden nodes exist and there is no base station. Each computer node hosts a set of sporadic message streams where a message stream releases messages with real-time deadlines. We propose a collision-free wireless medium access control (MAC) protocol which implements staticpriority scheduling. The MAC protocol allows multiple masters and is fully distributed. It neither relies on synchronized clocks nor out-of-band signaling; it is an adaptation to a wireless channel of the dominance protocol used in the CAN bus. But unlike that protocol, our protocol does not require a node having the ability to receive an incoming bit from the channel while transmitting to the channel. Our protocol has the key feature of not only being prioritized and collision-free but also dealing successfully with hidden nodes. This key feature enables schedulability analysis of sporadic message streams in multihop networks.

Synthesis of organometallic Ruthenium(II) complexes with strong activity against several human canceer cell lines

A new family of "RuCp" (Cp=eta(5)-C5H5) derivatives with bidentate N,O and N,N'-heteroaromatic ligands revealed outstanding cytotoxic properties against several human cell lines namely, A2780, A2780CisR, HT29, MCF7, MDAMB231, and PD. IC50 values were much lower than those found for cisplatin. Crystal structure of compound 4 was determined by X-ray diffraction studies. Density functional theory (DFT) calculations performed for compound 1 showed electronic flow from the ruthenium center to the coordinated bidentate ligand, in agreement with the electrochemical studies and the existence of a metal-to-ligand charge-transfer (MLCT) band evidenced by spectroscopic data.

Auditory event-related potentials in children with benign epilepsy with centro-temporal spikes

Benign focal epilepsy in childhood with centro-temporal spikes (BECTS) is one of the most common forms of idiopathic epilepsy, with onset from age 3 to 14 years. Although the prognosis for children with BECTS is excellent, some studies have revealed neuropsychological deficits in many domains, including language. Auditory event-related potentials (AERPs) reflect activation of different neuronal populations and are suggested to contribute to the evaluation of auditory discrimination (N1), attention allocation and phonological categorization (N2), and echoic memory (mismatch negativity – MMN). The scarce existing literature about this theme motivated the present study, which aims to investigate and document the existing AERP changes in a group of children with BECTS. AERPs were recorded, during the day, to pure and vocal tones and in a conventional auditory oddball paradigm in five children with BECTS (aged 8–12; mean = 10 years; male = 5) and in six gender and age-matched controls. Results revealed high amplitude of AERPs for the group of children with BECTS with a slight latency delay more pronounced in fronto-central electrodes. Children with BECTS may have abnormal central auditory processing, reflected by electrophysiological measures such as AERPs. In advance, AERPs seem a good tool to detect and reliably reveal cortical excitability in children with typical BECTS.

Fly by data link: feasibility of a relative navigation solution for aviation relying on a future L-band data link

Trabalho final de Mestrado para obtenção do grau de Mestre em Engenharia de Electrónica e Telecomunicações

Velocity estimation of moving ships using C-band SLC SAR data

A new algorithm for the velocity vector estimation of moving ships using Single Look Complex (SLC) SAR data in strip map acquisition mode is proposed. The algorithm exploits both amplitude and phase information of the Doppler decompressed data spectrum, with the aim to estimate both the azimuth antenna pattern and the backscattering coefficient as function of the look angle. The antenna pattern estimation provides information about the target velocity; the backscattering coefficient can be used for vessel classification. The range velocity is retrieved in the slow time frequency domain by estimating the antenna pattern effects induced by the target motion, while the azimuth velocity is calculated by the estimated range velocity and the ship orientation. Finally, the algorithm is tested on simulated SAR SLC data.

One Anastomosis Gastric Bypass versus Roux en Y Gastric Bypass as Salvage Technique after Failed Gastric Band: a Retrospective Analysis of 80 Cases

The classical “Roux en Y Gastric Bypass” (RYGBP) is still the standard technique between all the ones being used nowadays. The “One anastomosis gastric bypass” (OAGBP), is an evolution of the “Minigastic bypass” described by Robert Rutledge in 2001, is a well known and progressively frequent but still controversial technique. In our group, after an experience of 10 years using the RYGBP as a salvage surgery after failed gastric banding, in 132 cases, we decided to adopt the OAGBP as our preferential bariatric technique also in this situation. The theoretical main reasons for that shift are related to the increased safety, maximized weight loss, long term weight loss maintenance and reversibility of the operation. Method: Retrospectively we evaluated data of the surgical management of revisional cases for conversion, after failed or complicated gastric bands to gastric bypass. We selected the last 40 cases of each technique since May 2010. Results: All cases were performed by laparoscopy without any conversion. In both groups the conversion has been performed in one single step (17 cases, 42,5%). Data showed lower morbidity with OAGBP (2,5% against 7,5%) and better weight loss in theOAGBP cohort after a median follow up of 16months (67%against 55%) in patients revised after gastric band failure or complications. None had statistic significance (p>0,1) by the chi-square contingency table analysis.Conclusion: It seems to there is a difference in favour of OAGBP for conversion of complicated gastric bands. In this study we didn’t found statistic significance probably because of the short numbers. Prospective and more powerful studies are necessary to evaluate the benefit of the studied procedure.

Public private collaboration: Potentials for spatial data infrastructure development in developing countries - A caste study of Nigeria

Dissertation submitted in partial fulfillment of the requirements for the Degree of Master of Science in Geospatial Technologies.

Biochemical and spectroscopic characterization of the membrane-bound nitrate reductase from Marinobacter hydrocarbonoclasticus 617

J Biol Inorg Chem (2008) 13:1321–1333 DOI 10.1007/s00775-008-0416-1

Structural change in the ruhr region: problems, potentials and developments

Due to the decline of the heavy industries in the Ruhr region, the area has to reinvent itself. The orientation towards service industries proves to be a difficult task for the district and its population. This paper examines the challenges, problems and potentials of the Ruhr region against the backdrop of its economical history out of a sociological perspective. Thereby the economical situation and its outcome towards the population stand in the foreground of the paper.

Multipacket reception in the presence of in-band full-duplex communication

In-Band Full-DupleX (IB-FDX) is defined as the ability for nodes to transmit and receive signals simultaneously on the same channel. Conventional digital wireless networks do not implement it, since a node’s own transmission signal causes interference to the signal it is trying to receive. However, recent studies attempt to overcome this obstacle, since it can potentially double the spectral efficiency of current wireless networks. Different mechanisms exist today that are able to reduce a significant part of the Self- Interference (SI), although specially tuned Medium Access Control (MAC) protocols are required to optimize its use. One of IB-FDX’s biggest problems is that the nodes’ interference range is extended, meaning the unusable space for other transmissions and receptions is broader. This dissertation proposes using MultiPacket Reception (MPR) to address this issue and adapts an already existing Single-Carrier with Frequency-Domain Equalization (SC-FDE) receiver to IB-FDX. The performance analysis suggests that MPR and IB-FDX have a strong synergy and are able to achieve higher data rates, when used together. Using analytical models, the optimal transmission patterns and transmission power were identified, which maximize the channel capacity with the minimal energy consumption. This was used to define a new MAC protocol, named Full-duplex Multipacket reception Medium Access Control (FM-MAC). FM-MAC was designed for a single-hop cellular infrastructure, where the Access Point (AP) and the terminals implement both IB-FDX and MPR. It divides the coverage range of the AP into a closer Full-DupleX (FDX) zone and a farther Half-DupleX (HDX) zone and adds a tunable fairness mechanism to avoid terminal starvation. Simulation results show that this protocol provides efficient support for both HDX and FDX terminals, maximizing its capacity when more FDX terminals are used.

A radiofrequency identification system for the 60 GHz ISM band

Dissertação de mestrado integrado em Engenharia Biomédica (área de especialização em Eletrónica Médica)

A possible contribution to improving the therapeutic potentials of Babor's Typology of Alcohol Dependent Patients

ABSTRACT Objective The objective of this study was to replicate Babor's Typology and to explore clinical features related to personality traits that may underlie this classification, in order to improve its therapeutic possibilities. Methods Observational prospective study on a group of 273 male alcoholics. After a replication of Babor's variables, Cluster Analysis, Chi-Square – applied on clinical variables related to a Lappda Tipology – and Kappa tests were performed. Results The study identified two distinct clusters that held similar features to those described for the Type A/Type B classification. Besides presenting a lower socio-economic situation, Cluster 2 patients were associated with higher vulnerability and severe clinical features and also differed from Cluster 1 in their response to treatment. These replicated clusters retained connections and also differences in relation to the variables derived from the Lappda Typology. Conclusion Considering that each of the two replicated clusters seem to be associated to different personality traits – according to their correlations to the affective, cognitive and behavioral dimensions brought forward by the Lappda Typology – it is acceptable that this study may contribute to the development of more comprehensive and effective therapeutic strategies specifically tailored to target more specific personality traits of these subgroups of alcoholic patients.

Analysis of the effects of the continuous electrode paste band on precordial leads of the electrocardiogram

OBJECTIVE - To determine if the application of a continuous electrode paste band on precordial leads results in alteration of the electrocardiographic tracing as compared with an adequate amount of electrode paste, and if the former condition does not cause uniform morphologies from V1 to V6. METHODS - The amplitude and morphology of the electrocardiographic waves on the precordial leads in electrocardiographic tracings, which were performed with standard (control group) or excessive (continuous band) application of the electrode paste, were compared. RESULTS - None of the 106 patients studied showed uniformity of the QRS morphology from V1 to V6. The eletrocardiographic alterations identified in the tracings performed with a continuous electrode paste band that showed statistical significance in relation to the control group were the following: inversion of the P wave in V1; inversion of the T wave in V1, V2, and V3; appearance of R' waves in V1 and V2; disappearance of S waves in V1; appearance of S waves in V5 and V6; alterations in the amplitude of almost all waves, in all leads. CONCLUSION - Application of a continuous electrode paste band in the precordial leads may cause significant alterations in the electrocardiographic tracing obtained.

Analysis of the Prevalence of Ventricular Late Potentials in the Late Phase of Myocardial Infarction Based on the Site of Infarction

OBJECTIVE: The initial site of myocardial infarction (MI) may influence the prevalence of ventricular late potentials (VLP), high-frequency signals, due to the time course of ventricular activation. The prevalence of VLP in a period of more than 2 years after acute MI was assessed focusing on the initially injured wall . METHODS: The prevalence of VLP in a late phase after MI (median of 924 days) in anterior/antero-septal and inferior/infero-dorsal wall lesion was analyzed using signal-averaged electrocardiogram in time domain. The diagnostic performance of the filters employed for analysis on was tested at high-pass cut-off frequencies of 25 Hz, 40 Hz and 80 Hz. RESULTS: The duration of the ventricular activation and its terminal portion were larger in inferior than anterior infarction, at high-pass cut-off frequencies of 40 Hz and 80 Hz. In patients with ventricular tachycardia, these differences were more remarked. The prevalence of ventricular late potentials was three times greater in inferior than anterior infarction. CONCLUSION: Late after myocardial infarction, the prevalence and the duration of ventricular late potentials are greater in lesions of inferior/infero-dorsal than anterior/antero-septal wall confirming their temporal process, reflecting their high-frequency content.

Nordisches Plankton : botanischer teil, band 8, [hrsg. von K. Brandt und C. Apstein, unter Mitwirkung von Bergendal ... et al.].

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