Location and calculation-free node-scheduling schemes in large wireless sensor networks

In wireless sensor networks that consist of a large number of low-power, short-lived, unreliable sensors, one of the main design challenges is to obtain long system lifetime without sacrificing system original performance (sensing coverage and sensing reliability). To solve this problem, one of the potential approaches is to identify redundant nodes at the sensing interface and then assign them an off-duty operation mode that has lower energy consumption than the normal on-duty mode. In our previous work [J. Wireless Commun. Mobile Comput. 3 (2003) 271; Processing of ACM Wireless Sensor Network and Application Workshop 2002, September 2002], we proposed a node-scheduling scheme, which can provide a 100% sensing coverage preservation capability. This, however, requires each node to be aware of its own and its neighbors’ location information. Also, in that scheme, each node has to do accurate geometrical calculation to determine whether to take an off-duty status. In this paper, we propose and study several alternative node-scheduling schemes, which cannot completely preserve the original system coverage, but are nonetheless light-weighted and flexible compared with the previous one. Our simulation results compare these schemes with the previous one and demonstrate their effectiveness.     

A QoS index for IP services to effectively support usage-based charging

The goal of this letter is to present a model to compute a quality-of-service (QoS) index to characterize IP services. Then, we show how such a score may be used in a clear and flexible way for defining advanced usage-based tariff criteria to charge QoS guaranteed network services to address the dynamics of the expected future telecommunications scenario.     

The electropolymerization of pyrrole at a CuNi electrode: corrosion protection properties

Pyrrole was successfully electropolymerized at a copper–nickel electrode in a near-neutral sodium oxalate solution containing Cu²⁺ cations to generate a homogenous and adherent polypyrrole film. The presence of the Cu²⁺ ions increased both the rate of the electropolymerization reaction and the adherence of the polymer at the CuNi interface. In the absence of these cations, oxidation of the electrode occurred generating a nickel-rich layer that was not sufficiently conducting, under the electropolymerization conditions employed, to facilitate the electron-transfer reaction and the electropolymerization of pyrrole.These films remained stable and exhibited significant corrosion protection properties in acidified and neutral 0.1 mol dm⁻³ NaCl solutions even on polarization of the electrodes to high anodic potentials.     

The novel inotropic agent CGP 48506 alters force primarily by Ca(2+)-independent mechanisms in porcine skinned trabeculae

OBJECTIVES: The aim was to determine whether, and by what mechanism(s), a novel inotropic agent 5-methyl-6-phenyl-1,3,5,6-tetrahydro-3, 6-methano-1,5-benzodiazocine-2,4-dione (BA 41899) and its enantiomers directly alter the Ca2+ sensitivity of cardiac myofilaments. METHODS: Porcine ventricular trabeculae were permeabilised with Triton X-100. The relationship between force and pCa (-log[Ca2+]) was determined in the presence and absence of ATP. Troponin I was extracted, using vanadate, to produce unregulated maximally activated myofilaments. Force and actomyosin ATPase activity were measured simultaneously to determine tension cost (ATPase activity/tension). The effects of the (+) enantiomer (CGP 48506) on the twitch of intact muscle were demonstrated using rat papillary muscle. RESULTS: 100 microM BA 41899 had a pronounced Ca2+ sensitising effect on force production by porcine skinned cardiac fibres, increasing the pCa required for 50% maximal activation by 0.64 units, while suppressing maximum force by 18.3%. Resting tension was unaffected. These actions were primarily caused by CGP 48506 and were concentration dependent. At concentrations less than 100 microM, CGP 48506 also increased twitch amplitude in intact papillary muscles with no effect on resting tension, whereas 100 microM CGP 48506 increased resting force due to a slowing of relaxation. 100 microM CGP 48506 potentiated Ca(2+)-independent rigor tension in skinned trabeculae, indicating a Ca2+ sensitising mechanism unrelated to Ca2+ binding to troponin C. Tension cost was unaffected by 100 microM CGP 48506 over the entire range of activating Ca2+ concentrations. Suppression of maximum force by CGP 48506 was independent of both Ca2+ concentration and the regulatory troponin complex. CONCLUSIONS: Both the increase in Ca2+ sensitivity during submaximal activation and the depression of maximum force which are induced by CGP 48506 in skinned trabeculae occur at least partly through Ca(2+)-independent mechanisms.     

Morphological variations of the human gastric mucosa after omeprazole treatment: a scanning electron microscopic study

The effects of antiepileptic drugs on cognitive function in 48 healthy volunteers were assessed using event-related potentials (ERP) and the Attention Index included in the Wechsler Memory Scale, revised edition (WMS-R). The study was conducted over 1 week, using a double-blind design. Four drugs, carbamazepine (CBZ), phenytoin (PHT), valproate (VPA) and zonisamide (ZNS) were tested. Using an auditory oddball task, ERP measurements were made under two conditions with different tone intensities: Condition 1 used 70 db SPL; and Condition 2 used 30 db SPL. Results showed that CBZ prolonged target N1 and P3 latencies in Condition 1, and reduced frequent N1 amplitude in Condition 2, which suggests that CBZ may cause a change in sensory memory and prolong stimulus evaluation time. It is suggested that under a low stimulus intensity level, the sensory function itself was affected. Phenytoin was found to prolong target N1 latency in Condition 2, which also indicates a change in the sensory memory function. However, VPA did not significantly affect ERP components, except for the shortened frequent N1 latency, which could not be explained due to the limited information. It was found that ZNS augmented P3 amplitude in Condition 2, and reduced scores on the Attention Index. It is suggested that the augmentation of P3 amplitude was caused by the reduction of processing negativity as a result of the detrimental effect of ZNS on subjects' attention. However, the apparent difference between the ERP and behavioral indices suggests that caution should be exercised in assessing the results obtained only from ERP measurements.     

Assessment of the influence of the compliant aortic root on aortic valve mechanics by means of a geometrical model

In recent years several researchers have suggested that the changes in the geometry and angular dimensions of the aortic root which occur during the cardiac cycle are functional to the optimisation of aortic valve function, both in terms of diminishing leaflet stresses and of fluid-dynamic behaviour. The paper presents an analytical parametric model of the aortic valve which includes the aortic root movement. The indexes used to evaluate the valve behaviour are the circumferential membrane stress and the stress at the free edge of the leaflet, the index of bending strain, the bending of the leaflet at the line attachment in the radial and circumferential directions and the shape of the conduit formed by the leaflets during systole. In order to evaluate the role of geometric changes in valve performance, two control cases were considered, with different reference geometric configuration, where the movement of the aortic root was ignored. The results obtained appear consistent with physiological data, especially with regard to the late diastolic phase and the early ejection phase, and put in evidence the role of the aortic root movement in the improvement of valve behaviour.     

Apoptosis in the failing human heart

BACKGROUND: Loss of myocytes is an important mechanism in the development of cardiac failure of either ischemic or nonischemic origin. However, whether programmed cell death (apoptosis) is implicated in the terminal stages of heart failure is not known. We therefore studied the magnitude of myocyte apoptosis in patients with intractable congestive heart failure. METHODS: Myocardial samples were obtained from the hearts of 36 patients who underwent cardiac transplantation and from the hearts of 3 patients who died soon after myocardial infarction. Samples from 11 normal hearts were used as controls. Apoptosis was evaluated histochemically, biochemically, and by a combination of histochemical analysis and confocal microscopy. The expression of two proto-oncogenes that influence apoptosis, BCL2 and BAX, was also determined. RESULTS: Heart failure was characterized morphologically by a 232-fold increase in myocyte apoptosis and biochemically by DNA laddering (an indicator of apoptosis). The histochemical demonstration of DNA-strand breaks in myocyte nuclei was coupled with the documentation of chromatin condensation and fragmentation by confocal microscopy. All these findings reflect apoptosis of myocytes. The percentage of myocytes labeled with BCL2 (which protects cells against apoptosis) was 1.8 times as high in the hearts of patients with cardiac failure as in the normal hearts, whereas labeling with BAX (which promotes apoptosis) remained constant. The near doubling of the expression of BCL2 in the cardiac tissue of patients with heart failure was confirmed by Western blotting. CONCLUSIONS: Programmed death of myocytes occurs in the decompensated human heart in spite of the enhanced expression of BCL2; this phenomenon may contribute to the progression of cardiac dysfunction.     

Ascitic fluid analysis in hepatocellular carcinoma

BACKGROUND: Ascites in patients with hepatocellular carcinoma (HCC) is a poorly characterized subgroup of malignancy-related ascites. Not only the underlying liver disease, but also the tumor growth and spread contributes to the ascites formation. The authors differentiated ascites in HCC from other types of ascites. METHODS: The authors analyzed the ascitic fluid of 185 consecutive patients (89 liver cirrhosis, 33 HCC, 31 peritoneal carcinomatosis, 22 liver metastases, 10 spontaneous bacterial peritonitis). RESULTS: Each subgroup showed a typical pattern. Compared with the cirrhotic patients, those with HCC showed a higher frequency of positive cytologic findings (4 of 33 versus 0/89, P < 0.004), elevated fibronectin concentration (10/33 versus 8/89, P < 0.004), and elevated polymorphonuclear cell count (10/33 versus 5/89 P < 0.004). CONCLUSIONS: A significant number of patients with ascites and HCC patients showed signs of peritoneal infiltration with positive cytologic findings and increased concentration of fibronectin. Moreover, neutrocytic ascites without signs of superinfection is relatively common (30%).