Clinical Evaluation of Extracellular ADMA Concentrations in Human Blood and Adipose Tissue

Circulating asymmetrical dimethylarginine (ADMA), an endogenous inhibitor of nitric oxide synthesis, has been proposed as a biomarker for clinical outcome. Dimethylarginine dimethylaminohydrolase (DDAH) is the main enzyme responsible for ADMA metabolism and elimination. Adipose tissue ADMA concentrations and DDAH activity and their role in diabetes and obesity have not yet been investigated. In this study, we evaluated clinical microdialysis in combination with a sensitive analytical method (GC-MS/MS) to measure ADMA concentrations in extracellular fluid. Adipose tissue ADMA concentrations were assessed before and during an oral glucose tolerance test in lean healthy subjects and subjects with diabetes (n = 4 each), and in morbidly obese subjects before and after weight loss of 30 kg (n = 7). DDAH activity was determined in subcutaneous and visceral adipose tissue obtained during laparoscopic surgery (n = 5 paired samples). Mean interstitial ADMA concentrations did not differ between study populations (healthy 0.17 ± 0.03 μM; diabetic 0.21 ± 0.03 μM; morbidly obese 0.16 ± 0.01 and 0.17 ± 0.01 μM before and after weight loss, respectively). We did not observe any response of interstitial ADMA concentrations to the oral glucose challenge. Adipose tissue DDAH activity was negligible compared to liver tissue. Thus, adipose tissue ADMA plays a minor role in NO-dependent regulation of adipose tissue blood flow and metabolism.     

A nomogram method for estimating the energy produced by wind turbine generators

A simple nomogram is constructed to estimate the power generated by a wind turbine generator (WTG) operated at near maximum efficiency using optimum tip-speed ratio between cut-in and rated wind speed, and at constant power using optimum pitch control between rated and cut-out wind speed. The nomogram is based on information that is readily available for commercial WTGs as well as some simple statistical quantities for the wind at the site. When the wind speed is described by a Weibull distribution, the power of a WTG is estimated in terms of three generalized non-dimensional parameters. When a Rayleigh distribution is employed only two parameters are necessary. A second nomogram is also developed for those less common cases where a small correction of the results of the first nomogram is needed. A mathematical analysis is presented which allows for the construction of single chart nomograms without sacrificing the necessary accuracy. Two application examples demonstrate the degree of accuracy achieved by the nomograms and the advantages they offer for parametric analyses as regards convenience and labor.     

Solar and geothermal heating and cooling of the European Centre for Public Law building in Greece

The European Centre for Public Law in Legraina near Athens in Greece is heated and cooled by a combined solar and geothermal system. The main components of the system are a saline groundwater supplying well, water storage tank for 6 h autonomy, inverter for regulating geothermal flow, heat exchanger, two electrical water source heat pumps placed in cascade, fan coils, air handling units, as well as solar air collectors for air preheating in winter. In addition, hot water is supplied to the building hostel by solar water heaters. Monitoring of the energy system during heating showed excellent energy efficiency and performance.     

High performance,low complexity cooperative caching for wireless sensor networks

During the last decade, Wireless Sensor Networks have emerged and matured at such point that they currently support several applications such as environment control, intelligent buildings, target tracking in battlefields. The vast majority of these applications require an optimization to the communication among the sensors so as to serve data in short latency and with minimal energy consumption. Cooperative data caching has been proposed as an effective and efficient technique to achieve these goals concurrently. The essence of these protocols is the selection of the sensor nodes which will take special roles in running the caching and request forwarding decisions. This article introduces two new metrics to aid in the selection of such nodes. Based on these metrics, we propose two new cooperative caching protocols, PCICC and scaPCICC, which are compared against the state-of-the-art competing protocol, namely NICoCa. The proposed solutions are evaluated extensively in an advanced simulation environment and the results confirm that the proposed caching mechanisms prevail over its competitor. The evaluation attests also that the best policy is always scaPCICC, achieving the shortest latency and the least number of transmitted messages.     

On the Performance of TETRA Short Data Service-Transport Layer

This paper presents the results of an extensive measurement survey on the performance of Short Data Service Transport Layer (SDS-TL) of Terrestrial Trunked Radio (TETRA) cellular networks. We developed a novel software measurement platform that runs over the TETRA Peripheral Equipment Interface (PEI), generates SDS-TL traffic, performs measurements, and presents statistics of QoS metrics. The measurement platform was utilized in two measurement campaigns: in the first one, two terminals were co-located in the same TETRA cell, and in the second campaign the terminals were positioned in different cells. Measurements were taken for SDS-TL sizes varying from 10 to 190 bytes (excluding the TL header) with an increment of 5 bytes. For each SDS-TL size, 1,500 messages were exchanged through the measurement platform between the TETRA mobile terminals. We repeated all measurements for three intertransmission intervals, namely 2, 1.5, and 1 s, corresponding to measurement durations-for each set of 1,500 SDS-TL- of ≈ 3,000, 2,250 and 1,500 s, respectively. Hence, 166,500 SDS-TL messages were exchanged between two terminals for each measurement campaign. Results obtained include the end-to-end transmission delay (mean and standard deviation) and the percentage of lost SDS-TL versus the message size for the three intertransmission intervals. The effects of inadequate radio capacity as well as gaps in the radiocoverage can be easily identified through the measurement platform, and we analyze such representative cases.     

The three isentropic exponents of dry steam

The isentropic change of an ideal gas is described by the well known relations pv^k=const, Tv^(k−1) =const and p^(1−k)T^k=const, where the exponent k is defined as the ratio of the constant pressure to the constant volume specific heat, k=c_p/c_v. The same relations are also used for real gases if small or differential isentropic changes are considered. A better examination of the differential isentropic change shows that for p, v, T systems, there are three different isentropic exponents corresponding to each pair formed out of the variables p, v, T. These three exponents noted k_T,p, k_T,v, k_p,v after the corresponding pair of variables used, are interconnected by one relation, and accordingly only two out of the three are independent. The analysis of the present paper leads to the conclusion that calculations encountered in real gas isentropic change, with the exponent k taken as the ratio of the local specific heat values may lead to incorrect results. The numerical values of these exponents for steam, have been calculated and are presented. It can be seen that the deviations obtained, in comparison to the use of conventional k=c_p/c_v values are considerable.     

Surface wave dispersion in large concrete structures

The present paper discusses the repair characterization of large concrete surfaces based on the propagation of low-frequency elastic waves. A common repair method is cement injection. As a result, cracks and voids are eliminated increasing the measured average pulse velocity by about 5%. However, the central frequency of the pulses exhibits higher sensitivity to the repair increasing by about 15%. Additionally, the velocity of longitudinal waves exhibits a dependence on frequency. This dispersion is eliminated after repair being an indication of the repair efficiency, while Rayleigh waves are only slightly dispersive due to their long wavelength which enables them to travel below the shallow defects.     

Composition and antioxidant activity of essential oils from Oregano plants grown wild in Greece

In this study, four samples of essential oils obtained from plant species with a wide distribution in Greece and economic importance for the world-wide spice market and also carvacrol and thymol were tested for their possible antioxidant activity. The four plant species wereOriganum vulgare subsp.hirtum, O. onites, Coridothymus capitatus andSatureja thymbra. The essential oils were chemically characterised by gas chromatography-ion trap detection. All the essential oils examined and also carvacrol and thymol were found to have antioxidant activity when tested on TLC plates and by measuring peroxide values of lard stored at 35° C. The results indicate that the antioxidant effect may be related to the presence of carvacrol and thymol in essential oils.     

A practical method for the minimum weight design of stiffened plates under uniform lateral pressure

A method for the plastic analysis and minimum weight design of grillages and orthogonally stiffened plates subjected to lateral uniform pressure, and under a varying degree of rotational restraint at the supports, is presented. A computer aided design procedure for orthogonally stiffened rectangular plates based on this method is also described. This includes two optimization stages: overall optimization, in which the plastic moments for the beam in each set are found, and stiffener optimization, in which the optimum stiffener geometry is obtained. This design methodology has proved to be very efficient and easy to apply, and it is particularly valuable in the case of ship structures, where the maximum total number of panel stiffeners is in general not large.