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Selected AbstractsThe effects of torsion and motion coupling in site response estimationEARTHQUAKE ENGINEERING AND STRUCTURAL DYNAMICS, Issue 5 2003Mohammad R. Ghayamghamian Abstract Soil amplification characteristics are investigated using data from the Chibaken-Toho-Oki earthquake and its aftershocks recorded at Chiba dense array in Japan. The frequency-dependent amplification function of soil is calculated using uphole-to-downhole spectral ratio analysis, considering the horizontal components of shear wave. The identified spectral ratios consistently demonstrate the splitting of peaks in their resonance frequencies and low amplification values in comparison with a 1D model. The torsional behaviour and horizontal ground motion coupling are clarified as the reasons for these phenomena at the site. To prove the hypothesis, the torsional motion is directly evaluated using the data of the horizontal dense array in different depths at the site. The comparison between Fourier spectra of torsional motion and identified transfer functions reveals the peaks at the same frequencies. The wave equation including torsion and horizontal motion coupling is introduced and solved for the layered media by applying wave propagation theory. Using the developed model, the effects of torsional motion with horizontal motion coupling on soil transfer function are numerically examined. Splitting and low amplification at resonance frequencies are confirmed by the results of numerical analysis. Furthermore, the ground motion in two horizontal directions at the site is simulated using site geotechnical specification and optimizing the model parameters. The simulated and recorded motions demonstrate good agreement that is used to validate the hypothesis. In addition, the spectral density of torsional ground motions are compared with the calculated one and found to be well predicted by the model. Finally, the results are used to explain the overestimation of damping in back-calculation of dynamic soil properties using vertical array data in small strain level. Copyright © 2003 John Wiley & Sons, Ltd. [source] Microtubule displacements at the tips of living flagellaCYTOSKELETON, Issue 3 2002Geraint G. Vernon Abstract We have observed that the flagellar axoneme of the Chinese hamster spermatozoon undergoes periodic changes in length at the same frequency as the flagellar beat. The amplitude of the length oscillation recorded at the tip is maximally about 0.5 ,m or 0.2% of the total length. In some favourable cells, it was possible to see the opposing "halves" of the axoneme moving at the tip in a reciprocating manner and 180° out-of-phase. This behaviour, when analysed quantitatively, is broadly consistent with predictions made from the sliding-doublet theory of ciliary and flagellar motility and thus it constitutes an additional verification of the theory, for the first time in a living cell. However, on close examination, there is a partial mismatch between the timing of the length oscillation and the phase of the beat cycle. We deduce from this that there is some sliding at the base of the flagellum, sliding that is accommodated by elastic compression of the connecting piece. Micrographic evidence for such compression is presented. Cell Motil. Cytoskeleton 52:151,160, 2002. © 2002 Wiley-Liss, Inc. [source] Vectorial summation of probabilistic current harmonics in power systems: From a bivariate distribution model towards a univariate probability functionEUROPEAN TRANSACTIONS ON ELECTRICAL POWER, Issue 1 2000Y. J. Wang This paper extends the investigation into the bivariate normal distribution (BND) model which has been widely used to study the asymptotic behaviour of the sum of a sufficiently large number of randomly-varying harmonic phasors (of the same frequency). Although the BND model is effective and applicable to most problems involving harmonic summation, its main drawback resides in the computation time required to extract the probability density function of the harmonic magnitude from the two-dimensional BND model. This paper proposes a novel approach to the problem by assimilating the generalized Gamma distribution (GGD) model to the marginal distribution (the magnitude) of the BND using the method of moments. The proposed method can accurately estimate the parameters of the GGD model without time-consuming calculation. A power system containing ten harmonic sources is taken as an example where the comparison of the Monte-Carlo simulation, the BND model and the GGD model is given and discussed. The comparison shows that the GGD model approximates the BND model very well. [source] Influence of prey size on predation success by Zelus longipes L. (Het., Reduviidae)JOURNAL OF APPLIED ENTOMOLOGY, Issue 2-3 2002R. Cogni The effects of prey size on the predatory responses of the reduviid Zelus longipes were studied through laboratory tests using larvae of the noctuid moth Spodoptera frugiperda as preys. In tests with one caterpillar, larvae of three different weight classes were offered individually to the predator. The prey weight was positively correlated with relative weight gain by the predator, mean feeding time and discarded biomass, but not with the relative extraction rate (defined as the relative weight gain by the predator by feeding time). The different sizes of caterpillars were attacked with the same frequency, but the successful attacks were more frequent in small larvae. The median mass of successfully attacked larvae was also less than that of unsuccessfully attacked. In tests with three caterpillars, larvae of three weight classes were offered at the same time; small caterpillars were more often attacked and killed than the medium and large ones. The results showed that even if larger preys resulted in more energy intake, when the choice is possible, smaller caterpillars were more likely to be attacked than medium and large. This is probably related to the fact that successful attacks were more frequent in small larvae, and also reduced the risk of injury to the predator. [source] Frequency Analysis of Atrial Electrograms Identifies Conduction Pathways from the Left to the Right Atrium During Atrial Fibrillation,Studies in Two Canine ModelsJOURNAL OF CARDIOVASCULAR ELECTROPHYSIOLOGY, Issue 6 2009KYUNGMOO RYU Ph.D. Studies of atrial fibrillation (AF) have demonstrated that a stable rhythm of very short cycle length in the left atrium (LA) can cause fibrillatory conduction in the rest of the atria. We tested the hypothesis that fast Fourier transform (FFT) analysis of atrial electrograms (AEGs) during this AF will rapidly and reliably identify LA-to-right atrium (RA) conduction pathway(s) generated by the driver. Methods and Results: During induced atrial tachyarrhythmias in the canine sterile pericarditis and rapid ventricular pacing-induced congestive heart failure models, 380,404 AEGs were recorded simultaneously from epicardial electrodes on both atria. FFT analysis of AEGs during AF demonstrated a dominant frequency peak in the LA (driver), and multiple frequency peaks in parts of the LA and the most of the RA. Conduction pathways from the LA driver to the RA varied from study-to-study. They were identified by the presence of multiple frequency peaks with one of the frequency peaks at the same frequency as the driver, and traveled (1) inferior to the inferior vena cava (IVC); (2) between the superior vena cava and the right superior pulmonary vein (RSPV); (3) between the RSPV and the right inferior pulmonary vein (RIPV); (4) between the RIPV and the IVC; and (5) via Bachmann's bundle. Conduction pathways identified by FFT analysis corresponded to the conduction pathways found in classical sequence of activation mapping. Computation time for FFT analysis for each AF episode took less than 5 minutes. Conclusion: FFT analysis allowed rapid and reliable detection of the LA-to-RA conduction pathways in AF generated by a stable and rapid LA driver. [source] Effect of Temperature (,5 to 130 °C) and Fiber Direction on the Dielectric Properties of Beef Semitendinosus at Radio Frequency and Microwave FrequenciesJOURNAL OF FOOD SCIENCE, Issue 6 2008N. Basaran-Akgul ABSTRACT:, The dielectric properties must be defined to design efficient radio frequency (RF) and microwave (MW) processes by the food manufacturers. The objective of this study was to understand how frequency, temperature, and muscle fiber orientation influence the dielectric properties. The eye of round (Semitendinosus) muscle was selected because it contains large, relatively uniform muscle cells with similar muscle fiber orientation and relatively uniform chemical composition throughout the tissue. Dielectric properties were measured using an open-ended coaxial probe technique at 27, 915, and 1800 MHz and temperatures between ,5 and 130 °C. Power penetration depth was calculated. Since many commercially prepared, thermally processed, ready-to-eat entrees are made with frozen meat, dielectric property measurements were started from ,5 °C. The dielectric constant and dielectric loss factors were often higher for muscle with the muscle fiber measured in a parallel orientation to the probe compared to samples of the same treatment (for example, fresh or frozen) in a perpendicular tissue orientation at the same frequency and temperature. Dielectric constant and loss values for frozen beef tended to be higher than fresh beef at the same temperature and frequency. Tissue orientation appeared to have a greater effect on dielectric loss values at lower frequencies. Penetration depth tended to be greater when the direction of propagation was perpendicular to the muscle fiber. [source] Regulatory T cell activity in primary and persistent Epstein,Barr virus infectionJOURNAL OF MEDICAL VIROLOGY, Issue 5 2009P.J. Wingate Abstract Regulatory T cells (Treg) provide a balance to immune T cell activation thereby protecting the body from pathogen-induced immunopathology. Several persistent viruses induce Treg that subvert protective immune mechanisms and promote viral persistence. Epstein,Barr virus (EBV) generally infects children subclinically and persists thereafter, but primary infection in early adulthood may cause immunopathological damage manifest as infectious mononucleosis. In this study the role of Treg was investigated in acute infectious mononucleosis and healthy EBV seropositive donors. The proportion of CD4+CD25high T cells in blood from infectious mononucleosis patients was significantly lower than in seropositive donors (P,=,0.05). Using the FOXP3 marker for Treg the same frequency and extra-follicular distribution of Treg was noted in infectious mononucleosis and control tonsils. Regulatory cytokines, interleukin (IL)-10 and transforming growth factor (TGF)-,, were significantly raised in infectious mononucleosis compared to seropositive donor plasma (P,=,0.0001, P,=,0.0004 respectively) although levels of IL-10 peaked earlier in infectious mononucleosis than TGF-,. Previous studies identified EBV latent membrane protein (LMP)-1-induced Treg activity [Marshall et al. (2003): J Immunol 170:6183,6189; Marshall et al. (2007): Brit J Haematol 139:81,89], and in this study a significant reduction in interferon-, production was found from infectious mononucleosis but not seropositive donor lymphocytes after stimulation with a recall antigen when LMP-1 peptide PRG was added (P,=,0.03). It is possible that Treg are important in controlling primary EBV infection to a subclinical level in most cases and that infectious mononucleosis represents a failure of this protective mechanism. J. Med. Virol. 81:870,877, 2009. © 2009 Wiley-Liss, Inc. [source] Dual-mode bandpass filter using triangular patch resonator with inverted T-shaped slotMICROWAVE AND OPTICAL TECHNOLOGY LETTERS, Issue 12 2007Ariana L. C. Serrano Abstract This article presents a miniaturized dual-mode narrow bandpass filter using an equilateral triangular patch resonator with an inverted T-shaped slot, which exhibited a size reduction of 37% compared with a single-mode equilateral triangular patch at the same frequency. Two- and four-pole dual-mode bandpass filters were designed and fabricated with this new resonator. Experimental results with the two-pole filter centred at 7.76 GHz showed a fractional bandwidth of 4.5%, return loss better than 17.8 dB, and minimum insertion loss of 2.2 dB. The results of the four-pole filter showed a fractional bandwidth of 3.5%, return loss better than 16 dB, minimum insertion loss of 2.6 dB, and a good second harmonic band rejection. © 2007 Wiley Periodicals, Inc. Microwave Opt Technol Lett 49: 2897,2902, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.22927 [source] A compact narrow-band microstrip bandpass filter with a complementary split-ring resonatorMICROWAVE AND OPTICAL TECHNOLOGY LETTERS, Issue 10 2006Hung-Wei Wu Abstract This investigation proposes a compact bandpass filter (BPF) using a combination of the coupled uniform impedance resonator (CUIR) and the single complementary split-ring resonator (CSRR). Two transmission zeros of the proposed BPF can be controlled by tuning the dimension of CSRR at higher stopband. As operating at the same frequency, the size of the proposed BPF has a reduction of 26%, compared with the size of the conventional parallel coupled BPF. Measured results of the proposed BPF have good agreement with the electromagnetic simulated results. © 2006 Wiley Periodicals, Inc. Microwave Opt Technol Lett 48: 2103,2106, 2006; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.21865 [source] Signal enhancement in multiuser communication through adaptivity on transmitMICROWAVE AND OPTICAL TECHNOLOGY LETTERS, Issue 4 2003Abdellatif Medouri Abstract This paper presents a technique to enhance the received signals in a multiuser communication environment through the use of adaptivity on transmit. This technique is based on the principle of reciprocity and is independent of the material medium of transmission and the near-field environments. The objective here is to select a set of weights to be applied to each transmitting antenna, which is a function of the user location. The methodology is not a function of the multipath environment. Furthermore, the transmitted signal may be directed to a particular receiver location and simultaneously be minimized at other receiver locations while operating on the same frequency. Numerical simulations have been made to illustrate the novelty of the proposed approach. © 2003 Wiley Periodicals, Inc. Microwave Opt Technol Lett 38: 265,269, 2003; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.11034 [source] Rigid rotation of the solar core?MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY, Issue 4 2001On the reliable extraction of low-, rotational p-mode splittings from full-disc observations of the Sun We present low-, rotational p-mode splittings from the analysis of 8 yr of observations made by the Birmingham Solar-Oscillations Network (BiSON) of the full solar disc. These data are presented in the light of a thorough investigation of the fitting techniques used to extract them. Particular attention is paid to both the origin and magnitude of bias present in these estimates. An extensive Monte Carlo strategy has been adopted to facilitate this study , in all, several thousand complete, artificial proxies of the 96-month data set have been generated to test the analysis of real ,full-disc' data. These simulations allow for an assessment of any complications in the analysis which might arise from variations in the properties of the p modes over the 11-yr solar activity cycle. The use of such an extended data set affords greater precision in the splittings, and by implication the rotation rate inferred from these data, and reduces bias inherent in the analysis, thereby giving a more accurate determination of the rotation. The grand, weighted sidereal average of the BiSON set is , a value consistent with that expected were the deep radiative interior to rotate at the same frequency, and in the same ,rigid' manner, as the more precisely and accurately studied outer part of the radiative zone. [source] Sequence effects of disturbance on community structureOIKOS, Issue 2 2001Tadashi Fukami The sequence in which disturbance events occur has the potential to affect the structure of ecological communities, but its role has been generally overlooked. Most disturbance studies have focused on the frequency or intensity of disturbance, probably reflecting the influence of the intermediate disturbance hypothesis. To investigate the effects of disturbance sequence on community structure, I created laboratory microcosms of protists and small metazoans analogous to communities found in water-filled bamboo stumps. Using drought (disturbance D) and larval mosquito addition (disturbance M), I examined the following five treatments of disturbance sequence: D-M-D-M, D-D-M-M, M-D-M-D, M-M-D-D, and no disturbance as a control. The response of species to disturbance varied between disturbance types (D or M) as well as among species, and disturbance effects depended on previous disturbance events. As a result, disturbance sequence drove the microcosms onto different successional trajectories, sometimes leading to divergence in final community states in terms of species richness or species composition and relative abundance. This divergence occurred even under the same frequency and intensity of disturbance. These results suggest that historical information on disturbance sequence can be essential for explaining variation in community structure. The interaction of sequence with frequency and intensity likely enhances the role played by disturbance in ecological communities. [source] Adverse effects of neuromuscular blocking agents based on yellow card reporting in the U.K.: are there differences between males and females?,PHARMACOEPIDEMIOLOGY AND DRUG SAFETY, Issue 3 2006FRCA, Karen Patricia Light MBBS Abstract Background Adverse drug reactions (ADRs) are known to occur during anaesthesia; in the U.K. such ADRs may be reported through the Yellow Card Scheme (YCS). Our aim was to determine the demographics of ADRs to neuromuscular blocking drugs without formal causality assessment. Methods A retrospective analysis of ADRs to seven neuromuscular blocking drugs reported via the YCS during a greater than 30-year period was performed. Sex and age were analysed in order to identify at risk groups. Results Of 998 reports, 969 included gender. Non-allergic suspected reactions occurred with almost the same frequency as those with an allergic component. The majority occurred in females 676 (70%), and significant sex differences were measured between drugs. Males were more likely to have suffered an ADR to atracurium (p,=,0.01) whilst females experienced more ADRs to suxamethonium (p,=,0.01). ADRs proved fatal in 81 (9%) of the 950 reports for single drugs. Mortality following suxamethonium was significantly higher in males at 22% compared with 9% females (p,<,0.001). More women than men were reported to have allergic reactions, 73% (362/499) compared with 27% (137/499) respectively. The female:male ratio for ADRs was reversed for subjects <,10 years compared with peak ADR reports during the decade from 31,40 years. Conclusions Sex differences in mortality exist in this analysis. The unexpected high frequency of non-allergic ADRs suggests that morbidity and mortality from reactions to established drugs is twice that expected from allergic reactions alone. Standards and guidance for the reporting of ADRs warrant urgent development. Copyright © 2006 John Wiley & Sons, Ltd. [source] FT-Raman characterization of the antipodal bis-adduct of C60 and anthracenePHYSICA STATUS SOLIDI (B) BASIC SOLID STATE PHYSICS, Issue 11-12 2009Rudolf Pfeiffer Abstract We studied the mono- and the antipodal bis-adduct of C60 and anthracene with FT-Raman spectroscopy. Due to the reduced symmetry, the adducts have a much larger number of Raman-active modes than C60 with its icosahedral symmetry. Especially interesting is the fact that in the region of the C60 pentagonal pinch mode (PPM) the adducts show two strong peaks, of which the higher one is almost at the same frequency as the C60 mode and the lower one is downshifted by 5.4 and 10.5,cm,1 for the mono- and bis-adduct, respectively. The higher frequency peak could be explained by a degradation of the adducts into C60. However, calculated Raman spectra of the pure adducts also show two strong peaks in the PPM region, of which the higher frequency one is not PPM related. Finally, the C,H vibrations are the only clear evidence for anthracene in the adduct spectra. [source] Directional characteristics of the auditory system of cicadas: is the sound producing tymbal an integral part of directional hearing?PHYSIOLOGICAL ENTOMOLOGY, Issue 4 2004P. J. Fonseca Abstract. Directional hearing is investigated in males of two species of cicadas, Tympanistalna gastrica (Stål) and Tettigetta josei Boulard, that are similar in size but show different calling song spectra. The vibrational response of the ears is measured with laser vibrometry and compared with thresholds determined from auditory nerve recordings. The data are used to investigate to what extent the directional characteristic of the tympanal vibrations is encoded by the activity of auditory receptors. Laser measurements show complex vibrations of the tympanum, and reveal that directional differences are rather high (>15 dB) in characteristic but limited frequency ranges. At low frequencies, both species show a large directional difference at the same frequency (3,5 kHz) whereas, above 10 kHz, the directional differences correspond to the different resonant frequencies of the respective tymbals. Consequently, due to the mechanical resonance of the tymbal, the frequency range at which directional differences are high differs between the two species that otherwise show similar dimensions of the acoustic system. The directional differences observed in the tympanal vibrations are also observed in the auditory nerve activity. These recordings confirm that the biophysically determined directional differences are available within the nervous system for further processing. Despite considerable intra as well as interindividual variability, the ears of the cicadas investigated here exhibit profound directional characteristics, because the thresholds determined from recordings of the auditory nerve at 30° to the right and left of the longitudinal axis differ by more than 5 dB. [source] Ganglionic transmission in a vasomotor pathway studied in vivoTHE JOURNAL OF PHYSIOLOGY, Issue 9 2010Bradford Bratton Intracellular recordings were made in vivo from 40 spontaneously active cells in the third lumbar sympathetic ganglion of urethane-anaesthetized rats. In 38/40 cells ongoing action potentials showed strong cardiac rhythmicity (93.4 ± 1.9% modulation) indicating high barosensitivity and probable muscle vasoconstrictor (MVC) function. Subthreshold excitatory postsynaptic potentials (EPSPs) showed the same pattern. The 38 barosensitive neurons fired action potentials at 2.9 ± 0.3 Hz. All action potentials were triggered by EPSPs, most of which were unitary events. Calculations indicated that <5% of action potentials were triggered by summation of otherwise subthreshold EPSPs. ,Dominant' synaptic inputs with a high safety factor were identified, confirming previous work. These were active in 24/38 cells and accounted for 32% of all action potentials; other (,secondary') inputs drove the remainder. Inputs (21 dominant, 19 secondary) attributed to single preganglionic neurons fired at 1.38 ± 0.16 Hz. An average of two to three preganglionic neurons were estimated to drive each ganglion cell's action potentials. When cells were held hyperpolarized to block spiking, a range of spontaneous EPSP amplitudes was revealed. Threshold equivalent was defined as the membrane potential value that was exceeded by spontaneous EPSPs at the same frequency as the cell's original firing rate. In 10/12 cells examined, a continuum of EPSP amplitudes overlapped threshold equivalent. Small changes in cell excitability could therefore raise or lower the percentage of preganglionic inputs triggering action potentials. The results indicate that vasoconstrictor ganglion cells in vivo mostly behave not as 1:1 relays, but as continuously variable gates. [source] A study of departures from the inverse-barometer response of sea level to air-pressure forcing at a period of 5 daysTHE QUARTERLY JOURNAL OF THE ROYAL METEOROLOGICAL SOCIETY, Issue 597 2004E. L. Mathers Abstract The response of the sea level to atmospheric forcing is investigated through the cross-spectral analysis of tide-gauge data from around 100 island and deep-ocean stations and atmospheric pressure records. The focus is at a period of 5 days, coinciding with an atmospheric pressure oscillation (Madden,Julian wave) of the same frequency. Outside the Tropics the energy in synoptic weather systems masks the small amplitude of the pressure wave, resulting in a response indistinguishable from that of an inverse barometer (IB). Within the Tropics, variability of air pressure is smaller in comparison with the amplitude of the pressure wave and departures from the IB model are found. Analysis of several sub-surface pressure records in the tropical Atlantic also yields departures at this time-scale, and indicates the barotropic nature of the response. Findings from a near-global barotropic numerical model forced with realistic air pressure and wind-stress fields show reasonable agreement with results at tide-gauge locations, and provide a more complete view of the sea-level response. These results indicate the possibility of providing an improved simulation of sea-level response to atmospheric-pressure forcing at this time-scale than is currently provided by the IB model, for example in the field of satellite altimetry. Copyright © 2004 Royal Meteorological Society [source] TRANSFER OF FACIALLY INJURED ROAD TRAUMA VICTIMS AND ITS IMPACT ON TREATMENTANZ JOURNAL OF SURGERY, Issue 6 2005Martin Batstone Background: Road trauma is a common cause of severe facial injuries. The aim of the present study is to define patients involved, and determine the effect of their geographical origin on treatment and follow up. Methods: All patients over 14 years of age suffering facial injuries caused by road trauma presenting to the two study hospitals from 1994 to 1999 were identified and details were collected on demographic details and treatment. Results: Four hundred and nine patients met the inclusion criteria. The majority required hospital transfer. Young men were the most frequently injured group of patients. Patients from peripheral regions had significant delays in transfer and treatment. They were made fewer outpatient appointments but attended at the same frequency as patients from the immediate region of the study hospitals. Conclusions: To minimize delays the process of patient transfer needs to be streamlined and education of staff in peripheral hospitals undertaken regarding facial injuries. [source] Thinking and talking about the past: Why remember?APPLIED COGNITIVE PSYCHOLOGY, Issue 8 2009Susan Bluck Following functional theory, the focus of this paper is to examine individuals' reports of the functions that thinking and talking about the past serves in their daily lives. Younger and older men and women provided reports of the frequency with which they think and talk about their personal past to serve self-continuity, social-bonding and directing-behaviour functions. Younger and older adults endorsed the same frequency of using the past to maintain social bonds. In keeping with the context of their developmental life phase, including the need to forge self-concept clarity and their more open-ended perspective of the future, younger adults reported more often using autobiographical memory to create self-continuity and direct future plans. Copyright © 2009 John Wiley & Sons, Ltd. [source] GSM modulated radiofrequency radiation does not affect 6-sulfatoxymelatonin excretion of ratsBIOELECTROMAGNETICS, Issue 8 2003József Bakos Abstract In this study, the effect of exposure to 900 and 1800 MHz GSM-like radiofrequency radiation upon the urinary 6-sulfatoxymelatonin (6SM) excretion of adult male Wistar rats was studied. Seventy-two rats were used in six independent experiments, three of which were done with 900 MHz and the other three with 1800 MHz. The exposures were performed in a gigahertz transverse electromagnetic mode (GTEM) cell. The power densities of radiation were 100 and 20 ,W/cm2 at 900 and 1800 MHz frequency, respectively. The carrier frequency was modulated with 218 Hz, as in the GSM signal. The animals were exposed for 2 h between 8:00 AM and noon daily during the 14 day exposure period. The urine of rats was collected from 12:00 AM to 8:00 AM, collecting from exposed and control animal groups on alternate days. The urinary 6SM concentration was measured by 125I radioimmunoassay and was referred to creatinine. The combined results of three experiments done with the same frequency were statistically analyzed. Statistically significant changes in the 6SM excretion of exposed rats (n,=,18) compared to control group (n,=,18) were not found either at 900 or 1800 MHz. Bioelectromagnetics 24:531,534, 2003. © 2003 Wiley-Liss, Inc. [source] Partial-body exposure of human volunteers to 2450,MHz pulsed or CW fields provokes similar thermoregulatory responses,BIOELECTROMAGNETICS, Issue 4 2001Eleanor R. Adair Abstract Many reports describe data showing that continuous wave (CW) and pulsed (PW) radiofrequency (RF) fields, at the same frequency and average power density (PD), yield similar response changes in the exposed organism. During whole-body exposure of squirrel monkeys at 2450 MHz CW and PW fields, heat production and heat loss responses were nearly identical. To explore this question in humans, we exposed two different groups of volunteers to 2450,MHz CW (two females, five males) and PW (65,,s pulse width, 104,pps; three females, three males) RF fields. We measured thermophysiological responses of heat production and heat loss (esophageal and six skin temperatures, metabolic heat production, local skin blood flow, and local sweat rate) under a standardized protocol (30,min baseline, 45,min RF or sham exposure, 10,min baseline), conducted in three ambient temperatures (Ta,=,24, 28, and 31°C). At each Ta, average PDs studied were 0, 27, and 35,mW/cm2 (Specific absorption rate (SAR),=,0, 5.94, and 7.7,W/kg). Mean data for each group showed minimal changes in core temperature and metabolic heat production for all test conditions and no reliable differences between CW and PW exposure. Local skin temperatures showed similar trends for CW and PW exposure that were PD-dependent; only the skin temperature of the upper back (facing the antenna) showed a reliably greater increase (P,=,.005) during PW exposure than during CW exposure. Local sweat rate and skin blood flow were both Ta - and PD-dependent and showed greater variability than other measures between CW and PW exposures; this variability was attributable primarily to the characteristics of the two subject groups. With one noted exception, no clear evidence for a differential response to CW and PW fields was found. Bioelectromagnetics 22:246,259, 2001. © 2001 Wiley-Liss, Inc. [source] Generation and propagation of gastric slow wavesCLINICAL AND EXPERIMENTAL PHARMACOLOGY AND PHYSIOLOGY, Issue 4 2010Dirk F Van Helden Summary 1. Mechanisms underlying the generation and propagation of gastrointestinal slow wave depolarizations have long been controversial. The present review aims to collate present knowledge on this subject with specific reference to slow waves in gastric smooth muscle. 2. At present, there is strong agreement that interstitial cells of Cajal (ICC) are the pacemaker cells that generate slow waves. What has been less clear is the relative role of primary types of ICC, including the network in the myenteric plexus (ICC-MY) and the intramuscular network (ICC-IM). It is concluded that both ICC-MY and ICC-IM are likely to serve a major role in slow wave generation and propagation. 3. There has been long-standing controversy as to how slow waves ,propagate' circumferentially and down the gastrointestinal tract. Two mechanisms have been proposed, one being action potential (AP)-like conduction and the other phase wave-based ,propagation' resulting from an interaction of coupled oscillators. Studies made on single bundle gastric strips indicate that both mechanisms apply with relative dominance depending on conditions; the phase wave mechanism is dominant under circumstances of rhythmically generating slow waves and the AP-like propagation is dominant when the system is perturbed. 4. The phase wave mechanism (termed Ca2+ phase wave) uses cyclical Ca2+ release as the oscillator, with coupling between oscillators mediated by several factors, including: (i) store-induced depolarization; (ii) resultant electrical current flow/depolarization through the pacemaker cell network; and (iii) depolarization-induced increase in excitability of downstream Ca2+ stores. An analogy is provided by pendulums in an array coupled together by a network of springs. These, when randomly activated, entrain to swing at the same frequency but with a relative delay along the row giving the impression of a propagating wave. 5. The AP-like mechanism (termed voltage-accelerated Ca2+ wave) propagates sequentially like a conducting AP. However, it is different in that it depends on regenerative store Ca2+ release and resultant depolarization rather than regenerative activation of voltage-dependent channels in the cell membrane. 6. The applicability of these mechanisms to describing propagation in large intact gastrointestinal tissues, where voltage-dependent Ca2+ entry is also likely to be functional, is discussed. [source] Public health impact of isoniazid-resistant Mycobacterium tuberculosis strains with a mutation at amino-acid position 315 of katG: a decade of experience in The NetherlandsCLINICAL MICROBIOLOGY AND INFECTION, Issue 8 2006H. R. Van Doorn Abstract A previous limited study demonstrated that Mycobacterium tuberculosis isolates with a mutation at amino-acid position 315 of katG (,315) exhibited high-level resistance to isoniazid and were more frequently resistant to streptomycin. In the present study, isoniazid-resistant M. tuberculosis isolates from 8332 patients in The Netherlands (1993,2002) were screened for the ,315 mutation. Isoniazid resistance was found in 592 (7%) isolates, of which 323 (55%) carried ,315. IS6110 restriction fragment length polymorphism analysis showed that ,315 isolates occurred in clusters, suggesting recent transmission, at the same frequency as isoniazid-susceptible isolates. In contrast, other isoniazid-resistant isolates clustered significantly less frequently. ,315 isolates were high-level isoniazid-resistant, streptomycin-resistant and multidrug-resistant significantly more often, and may have a greater impact on public health, than other isoniazid-resistant isolates. [source] AN EFFICIENT MODEL FOR ENHANCING TEXT CATEGORIZATION USING SENTENCE SEMANTICSCOMPUTATIONAL INTELLIGENCE, Issue 3 2010Shady Shehata Most of text categorization techniques are based on word and/or phrase analysis of the text. Statistical analysis of a term frequency captures the importance of the term within a document only. However, two terms can have the same frequency in there documents, but one term contributes more to the meaning of its sentences than the other term. Thus, the underlying model should identify terms that capture the semantics of text. In this case, the model can capture terms that present the concepts of the sentence, which leads to discovering the topic of the document. A new concept-based model that analyzes terms on the sentence, document, and corpus levels rather than the traditional analysis of document only is introduced. The concept-based model can effectively discriminate between nonimportant terms with respect to sentence semantics and terms which hold the concepts that represent the sentence meaning. A set of experiments using the proposed concept-based model on different datasets in text categorization is conducted in comparison with the traditional models. The results demonstrate the substantial enhancement of the categorization quality using the sentence-based, document-based and corpus-based concept analysis. [source] | ||||||||||||||||||||||