Total Power Values Research Articles

Surface, electrical and mechanical modifications of PMMA after implantation with laser produced iron plasma ions

Laser Produced Plasma (LPP) was employed as an ion source for the modifications in surface, electrical and mechanical properties of poly methyl (methacrylate) PMMA. For this purpose Nd:YAG laser (532nm, 6ns, 10Hz) at a fluence of 12.7J/cm2 was employed to generate Fe plasma. The fluence and energy measurements of laser produced Fe plasma ions were carried out by employing Thomson Parabola Technique in the presence of magnetic field strength of 0.5T, using CR-39 as Solid State Nuclear Track Detector (SSNTD). It has been observed that ion fluence ejecting from ablated plasma was maximum at an angle of 5° with respect to the normal to the Fe target surface. PMMA substrates were irradiated with Fe ions of constant energy of 0.85MeV at various ion fluences ranging from 3.8×106ions/cm2 to 1.8×108ions/cm2 controlled by varying laser pulses from 3000 to 7000. Optical microscope and Scanning Electron Microscope (SEM) were utilized for the analysis of surface features of irradiated PMMA. Results depicted the formation of chain scission, crosslinking, dendrites and star like structures. To explore the electrical behavior, four probe method was employed. The electrical conductivity of ion irradiated PMMA was increased with increasing ion fluence. The surface hardness was measured by shore D hardness tester and results showed the monotonous increment in surface hardness with increasing ion fluence. The increasing trend of surface hardness and electrical conductivity with increasing Fe ion fluence has been well correlated with the surface morphology of ion implanted PMMA. The temperature rise of PMMA surface due to Fe ion irradiation is evaluated analytically and comes out to be in the range of 1.72×104 to 1.82×104K. The values of total Linear Energy Transfer (LET) or stopping power of 0.8MeV Fe ions in PMMA is 61.8eV/Å and their range is 1.34μm evaluated by SRIM simulation.

Impact of Renewable Energy Sources on the German Power System

In Germany due to the continuous high expansion of the intermittent power supply capabilities of wind turbines and photovoltaic systems, the operational modes of thermal generation units will be influenced essentially until 2020 and beyond. With the renewable energy sources (e.g. wind power (WP) and photovoltaic (PV)) in power system increase, the conventional power plants on line will be replaced by WP and PV. Thus, the sources of conventional reserve available to the system will be reduced and fewer conventional plants will be available online to share the regulation burden. Therefore the acceleration time constant is reduced if some of the conventional power plant generators with inertia (masses) are disconnected and replaced by the intermittent generators while the total nominal power value of the whole system remains constant. With the reduction of inertia not only the frequency deviation after disturbances will increase substantially but also more oscillation occurs which causes reduction in system stability. Therefore different scenarios of Renewable Energy sources will be presented and for the investigation of the system stability influenced by the primary control of the remaining conventional power plants the following mathematical methods are useful and have been used nonlinear dynamic simulation andl inear eigenvalue calculation. The models were created using MATLAB / Simulink software. Keywords: Inertia, oscillation, photovoltaic, renewable energy sources, stability, wind.

Evaluation of heart rate variability in patients with coronary artery ectasia and coronary artery disease.

The present study compared heart rate variability (HRV) parameters in patients with coronary artery ectasia (CAE) and coronary artery disease (CAD). The study population consisted of 60 consecutive patients with CAE (14 women; mean age 51.63±7.44 years), 60 consecutive patients with CA (15 women; mean age 53.67±9.31 years), and 59 healthy individuals (13 women; mean age 52.85±8.19 years). Electrocardiograms, 24-hour Holter analyses, and routine biochemical tests were performed, and clinical characteristics were evaluated. Coronary angiography images were analyzed. Time-domain HRV parameters, including the standard deviation (SD) of normal-to-normal intervals (SDNN) and the root mean square of difference in successive normal-to-normal intervals (RMSSD) were evaluated, as were frequency-domain HRV parameters including low-frequency (LF), very low-frequency (VLF), high-frequency (HF), the proportion derived by dividing low- and high-frequency (LF/HF), and total power (TP). SDNN was lower in both the CAE and CAD groups, compared to the healthy group (140.85±44.21, 96.51±31.28, and 181.05±48.67, respectively). A significant difference in RMSSD values among the groups was determined (p=0.004). Significantly decreased VLF and HF values were found in the CAE group, compared with the healthy group (VLF p<0.001; HF, p=0.007). TP, VLF, and HF values were significantly lower (p<0.001, p<0.001, and p<0.001, respectively), but LF and LF/HF values were significantly higher (p<0.001 for both) in the CAD group than in the healthy group. TP values were significantly higher (p<0.001), and LF and LF/HF values were lower in the CAE group, compared with the CAD group (p<0.001 for both). A decrease in vagal modulation or an increase in sympathetic activity of cardiac function, assessed by HRV analysis, is worse in patients with CAD than in patients with CAE.

The effects of the duration of mobile phone use on heart rate variability parameters in healthy subjects.

Objective:This study aimed to estimate the influence of the duration of mobile phone use on heart rate variability (HRV) in healthy individuals.Methods:One hundred forty-eight individuals without any established systemic disease and who had undergone 24-h ambulatory ECG monitoring were included in the case-control study. All the individuals had been using mobile phones for more than 10 years. Three-channel 24-h Holter monitoring was performed to derive the mean heart rate, standard deviation of normal NN intervals (SDNN), standard deviation of 5-min (m) mean NN intervals (SDANN), the proportion of NN50 divided by the total number of NNs (pNN50), the root mean square differences of successive NN intervals (RMSSD), high (HF)-, low (LF)-, very low (VLF)-frequency power, total power components, and the LF/HF ratio. Individuals were divided into four groups according to their duration of mobile phone use [no mobile phone use (Control group), <30 min/day (Group 1), 30–60 min/day (Group 2), and >60 min/day (Group 3)].Results:All the groups had similar features with regard to demographic and clinical characteristics. No significant arrhythmias were observed in any of the groups. The LF/HF ratio was higher, whereas the SDNN, SDANN, RMSSD, and pNN50 values were lower in the study groups than in the control group (p<0.05). No significant differences were identified among groups with respect to heart rate, VLF, and total power values (p>0.05).Conclusion:In this study, it was shown that the duration of mobile phone use may affect the autonomic balance in healthy subjects. The electromagnetic field created by mobile phone use may induce HRV changes in the long term.

Comparison of the effect of Physical stressor and Mental stressor in evaluation of the effect of progressive muscle relaxation on the cardiovascular autonomic functions in offsprings of hypertensives

Background and Objective: Progressive muscle relaxation is one of the techniques found to be effective in reducing the hyperacivity of the sympathetic nervous system in susceptible individuals. Many studies have used physical and mental stressors to evaluate the effect of relaxation techniques leading to different results. Hence the present study compared the effect of two laboratory stressors in the evaluation of effect of relaxation techniques. Materials and Methods: The study involved normotensive offspring of hypertensives who were participants of relaxation training programme at Bengaluru. They were divided into group A and group B with 20 subjects in each group by randomization. There were two recording sessions for each subject in each group. During the first recording session HR, HRV and BP responses to mental stress (serial subtraction math) were measured in all the subjects in group A, whereas in group B, HR, HRV and BP responses to physical stress (isometric handgrip test) were measured. Then both the groups underwent twelve weeks of relaxation training under the guidance of experts. At the end of twelve weeks, second recording session was held and the same parameters were reassessed in all the subjects with respective stressors. Results: In group A, relaxation training has caused significant decline in heart rate reactivity, reactivity values of total power, LF power, reactivity as well as recovery of diastolic pressure. No significant change was seen in LFnu, HF, HFnu, LF/HF and systolic blood pressure. In group B, no significant change was observed in any of the measured parameters. Conclusion: Hence the study concludes that mental stressor is the suitable tool for assessing the effect of relaxation techniques on the cardiovascular autonomic activity. Keywords: Mental stressor, Physical stressor, Progressive muscle relaxation, Heart rate, Heart rate variability, Blood pressure, Reactivity, Recovery

Corneal powers measured with a rotating Scheimpflug camera

Background/aimKeratometry measures the anterior corneal curvature only. Corneal power is calculated by multiplication with the keratometric refractive index, which takes into account the average negative posterior corneal power. The aim...

Refractive cylinder outcomes after calculating toric intraocular lens cylinder power using total corneal refractive power.

PurposeTo determine whether the total corneal refractive power (TCRP) value, which is based on measurement of both anterior and posterior corneal astigmatism, is effective for toric intraocular lens (IOL) calculation with AcrySof® Toric IOLs.Patients and methodsA consecutive series of cataract surgery cases with AcrySof toric IOL implantation was studied retrospectively. The IOLMaster® was used for calculation of IOL sphere, the Pentacam® TCRP 3.0 mm apex/ring value was used as the keratometry input to the AcrySof Toric IOL Calculator and the VERION™ Digital Marker for surgical orientation. The keratometry readings from the VERION reference unit were recorded but not used in the actual calculation. Vector differences between expected and actual residual refractive cylinder were calculated and compared to simulated vector errors using the collected VERION keratometry data.ResultsIn total, 83 eyes of 56 patients were analyzed. Residual refractive cylinder was 0.25 D or lower in 58% of eyes and 0.5 D or lower in 80% of eyes. The TCRP-based calculation resulted in a statistically significantly lower vector error (P<0.01) and significantly more eyes with a vector error ≤0.5 D relative to the VERION-based calculation (P=0.02). The TCRP and VERION keratometry readings suggested a different IOL toric power in 53/83 eyes. In these 53 eyes the TCRP vector error was lower in 28 cases, the VERION error was lower in five cases, and the error was equal in 20 cases. When the anterior cornea had with-the-rule astigmatism, the VERION was more likely to suggest a higher toric power and when the anterior cornea had against-the-rule astigmatism, the VERION was less likely to suggest a higher toric power.ConclusionUsing the TCRP keratometry measurement in the AcrySof toric calculator may improve overall postoperative refractive results. Consideration of measured posterior corneal astigmatism, rather than a population-averaged value, appears advantageous.

Electrophysiological and behavioural responses of turbot (Scophthalmus maximus) cooled in ice water

Behavioural, neural and physiological aspects related to pre-slaughter cooling of turbot habituated to two environmental temperatures (18.7 and 12.0°C) were investigated. Six fish in both treatments were immersed in ice water for 75min. For control, four fish were immersed in water under their habituated environmental temperature.Turbot did not show a quick reduction of overall power in the EEG (electroencephalogram) to less than 10%, nor did the turbot show a shift in brain wave predominance from high to low frequency waves. At 15min after immersion in ice water at least 7 out of 12 fish still showed total power values over 10% of pre-immersion values. Significant reductions in responsiveness to needle scratches and reduced breathing after immersion in ice water were observed, but none of these parameters had dropped to 0 even after 75min in ice water. A significant reduction in gill score was found at 2 and 5min after immersion in ice water compared to the control fish (p<0.05). Heart rates significantly increased immediately after immersion in ice water and then decreased to a low basal value 30min after immersion. The heart beat did not show major changes in regularity over time. Finally, at 15 and 75min the turbot in ice water were significantly more responsive to vibration than to needle scratches.From these results we conclude that immersion in ice water may not induce unconsciousness, however, the brain activity does decrease to a lower level. The implication of this low brain activity with respect to welfare is not clear. Increased heart rates and maintained low brain activity and response to needle scratches during early immersion in ice water are indicative of a stress response appearing to affect welfare negatively.

Objective assessment of postural stability in Parkinson's disease using mobile technology.

A significant gap remains in the ability to effectively characterize postural instability in individuals with Parkinson's disease. Clinical evaluation of postural declines is largely subjective, whereas objective biomechanical approaches are expensive and time consuming, thus limiting clinical adoption. Recent advances in mobile devices present an opportunity to address the gap in the quantification of postural stability. The aim of this project was to determine whether kinematic data measured by hardware within a tablet device, a 3rd generation iPad, was of sufficient quantity and quality to characterize postural stability. Seventeen patients and 17 age-matched controls completed six balance conditions under altered surface, stance, and vision. Simultaneous kinematic measurements were gathered from a three-dimensional motion capture system and tablet. The motion capture system and tablet provided similar measures of stability across groups. In particular, within the patient population, correlation between the two systems for peak-to-peak, normalized path length, root mean square, 95% volume, and total power values ranged from 0.66 to 1.00. Kinematic data from five balance conditions--double-leg stance with eyes open on a foam surface, double-leg stance with eyes closed on firm and foam surfaces, and tandem stance on firm and foam surfaces--were capable of discriminating patients from controls. The hardware within the tablet provides data of sufficient accuracy for the quantification of postural stability in patients with Parkinson's disease. The objectivity, portability, and ease of use of this device make it ideal for use in clinical environments lacking sophisticated biomechanical systems.

Heart rate variability analysis during head-up tilt test predicts nitroglycerine-induced syncope

ObjectiveThe aim of this study was to determine whether or not heart rate variability (HRV) analysis during the first 20 min of head-up tilt testing could predict whether patients will...

Effects of cold exposure on autonomic changes during the last rapid eye movement sleep transition and morning blood pressure surge in humans

BackgroundVarious studies have linked the occurrence of cardiovascular events and low ambient temperatures as well as the morning blood pressure surge (MBPS). We hypothesized that low ambient temperatures produce a higher sympathetic change during the last rapid eye movement (REM) sleep transition and that this may play an important role in cold-related cardiovascular events. MethodsAll experiments were carried out on 12 healthy male adults, aged 24.00±0.74years, who participated in two experimental conditions randomly (>1day apart): warm (23°C) and cold (16°C). Blood pressure (BP) was measured every 30min for 24h by autonomic ambulatory BP monitoring. The electroencephalograms, electrocardiograms, ambient temperature, near-body temperature, and physical activity were recorded by miniature polysomnography for 24h. ResultsThe cold conditions resulted in: (i) higher MBPS than under warm conditions; (ii) significant and greater sympathetic index changes during the sleep–wake transition than during cover-to-uncover and supine-to-sit position tests; (iii) the non-REM–REM transition-related sympathetic elevation during the cold conditions being significantly higher in late sleep period than in early sleep period; (iv) at 1h prior to morning awakening, the value of total power of heart rate variability changes being significantly negatively correlated with the changes of near-body temperature; and (v) significantly higher arousal index and shorter average interval of REM periods than in warm conditions. ConclusionCold exposure elevates the amplitude of MBPS and is associated with late sleep stage transition sympathetic activation, which might have important implications for cold-related cardiovascular events.

Assessment of cardiac autonomic function in patients with Duchenne muscular dystrophy using short term heart rate variability measures

BackgroundDuchenne muscular dystrophy (DMD) is a hereditary neuromuscular disorder frequently associated with progressive cardiac dysfunction, and is one of the common causes of death in these children. Early diagnostic markers of cardiac involvement might help in timely intervention. In this study we compared the short term HRV measures of DMD children with that of healthy subjects. MethodOne hundred and twenty-four genetically confirmed boys with DMD and 50 age matched controls were recruited. Error-free, electrocardiogram was recorded in all subjects at rest in the supine position. HRV parameters were computed in time and frequency domains. Time domain measures included standard deviation of NN interval (SDNN), and root of square mean of successive NN interval (RMSSD). Frequency domain consisted of total, low frequency and high frequency power values. Ratio of low frequency and high frequency power values (LF/HF) was determined using customized software. ResultsHRV parameters were significantly altered in DMD children as compared to healthy controls. Following parameters [mean (SD)] were reduced in DMD as compared to controls; RMSSD (in ms) [52.14 (33.2) vs 64.64 (43.2); p = 0.038], High frequency component (nu) [38.77 (14.4) vs 48.02 (17.1); p = 0.001] suggesting a loss of vagal tone. In contrast, measure of sympathovagal balance LF/HF [1.18 (0.87) vs 0.89 (0.79); p = 0.020] was increased in DMD group. ConclusionIn this cross sectional study we have demonstrated alteration in autonomic tone in DMD. Loss of vagal tone and an increase in sympathetic tone were observed in DMD children. Further prospective studies are required to confirm the utility of these measures as predictors of adverse cardiac outcome in DMD.

The influence of pemirolast on autonomic imbalance in rat cystitis model

Abstract Cyclophosphamide (CP) treatment is associated with the risk of haemorrhagic cystitis (HC). Moreover, CP-induced HC is complicated by autonomic nervous system (ANS) dysfunction. Pemirolast is thought to be a mast cell stabiliser that inhibits the release of many inflammatory mediators and sensory neuropeptides, and thus, it may be considered a potential chemoprotective HC agent. The aim of the study was to indirectly estimate the effect of pemirolast in experimental HC by measuring ANS activity with the heart rate variability (HRV) method. In CP-treated rats, we found a decreasing trend of overall autonomic activity, together with an imbalance between the main components, and a dominant very low frequency (VLF) power component. Pemirolast treatment did not improve the total HRV power value or the main non-normalized HRV components. Moreover, CP-HC animals treated with pemirolast displayed a different disproportion of normalized spectral components as compared to both control and CP-HC animals without pemirolast treatment, with the balance between normalized low frequency (nLF) and normalized high frequency (nHF) shifted towards nLF. This finding, together with a relatively high VLF tension, indicates that the pemirolast treatment resulted in high sympathetic activity that may contribute to HC exacerbation; thus, this agent seems to be ineffective in CP-induced HC.

Heart rate variability of transported critically ill neonates

Determining heart rate variability (HRV) in infants is a useful measure of physiological stability. Transport of ill neonates imposes a measurable degree of stress. A prospective observational study on 58 critically ill neonates, transported to an intensive care unit (ICU) was performed. HRV during the 24-h period before, during and after transport, heart rate (HR), mean arterial pressure and transport risk index of physiologic stability (TRIPS) score were observed. The median HRV total power value of 40.80 ms(2) was set as the cutoff value, and neonates with values below this were designated as the low-HRV group (l-HRV; n=29), and those above this as the high-HRV group (h-HRV; n=29). The h-HRV group had a significantly lower HR at retrieval and 1 h after admission and a significant 2- and 4-day shorter duration of mechanical ventilation and ICU treatment compared to the l-HRV group. Spearman's correlations between total power and duration of mechanical ventilation (ρ=-0.346; P<0.01) and ICU treatment (ρ=-0.346; P<0.01) were significant. Transported neonates were also tested for differences in HRV and other physiological and demographic parameters between the transport mode and time. No differences were found, except that the nighttime ambulance group had a statistically higher HRV compared to the daytime ambulance group. Higher HRV of group of neonates, who did not differ in illness severity TRIPS score from the lower HRV group, is associated with a faster and significant decrease in HR after transport and a 2- and 4-day shorter duration of mechanical ventilation and ICU treatment.

Accelerometric comparison of the locomotor pattern of horses sedated with xylazine hydrochloride, detomidine hydrochloride, or romifidine hydrochloride

To evaluate the duration of effects on movement patterns of horses after sedation with equipotent doses of xylazine hydrochloride, detomidine hydrochloride, or romifidine hydrochloride and determine whether accelerometry can be used to quantify differences among drug treatments. 6 healthy horses. Each horse was injected IV with saline (0.9% NaCl) solution (10 mL), xylazine diluted in saline solution (0.5 mg/kg), detomidine diluted in saline solution (0.01 mg/kg), or romifidine diluted in saline solution (0.04 mg/kg) in random order. A triaxial accelerometric device was used for gait assessment 15 minutes before and 5, 15, 30, 45, 60, 75, 90, 105, and 120 minutes after each treatment. Eight variables were calculated, including speed, stride frequency, stride length, regularity, dorsoventral power, propulsive power, mediolateral power, and total power; the force of acceleration and 3 components of power were then calculated. Significant differences were evident in stride frequency and regularity between treatments with saline solution and each α2-adrenoceptor agonist drug; in speed, dorsoventral power, propulsive power, total power, and force values between treatments with saline solution and detomidine or romifidine; and in mediolateral power between treatments with saline solution and detomidine. Stride length did not differ among treatments. Accelerometric evaluation of horses administered α2-adrenoceptor agonist drugs revealed more prolonged sedative effects of romifidine, compared with effects of xylazine or detomidine. Accelerometry could be useful in assessing the effects of other sedatives and analgesics. Accelerometric data may be helpful in drug selection for situations in which a horse's balance and coordination are important.

Effect of various forms of physical training on the autonomic nervous system activity in patients with acute myocardial infarction

A shift in the dynamic autonomic nervous system (ANS) balance towards sympathetic activity in patients with acute myocardial infarction (AMI) predisposes them to life-threatening ventricular arrhythmias. Improvement of unfavourable changes in ANS can be expected in such patients as a result of physical training. A beneficial shift in ANS balance towards parasympathetic activity could be confirmed by demonstrating increased baroreceptor reflex sensitivity (BRS) as well as favourable changes in heart rate variability (HRV) parameters. To analyse the effect of different forms of physical training on ANS activity in patients with AMI after hospital discharge. The study included 38 patients with AMI (aged 59 ± 8 years) subjected to 2-month exercise training. Group 1 (n = 19)underwent 3-week supervised in-hospital cardiac rehabilitation followed by 5-week home-based training, and Group 2 (n = 19) underwent 8-week home-based training. BRS and HRV were determined based on a 10-min recording of systolic arterial pressure and the cardiac cycle. Measurements were performed one day before discharge (R1) and after 2 months of training (R2). A significant increase in the mean values of TP (total power), HF (high frequency power), rMSSD (square root of the mean of the squared differences between successive R-R intervals), and pNN50 (proportion of differences between successive R-R intervals that are greater than 50 ms) was observed in the overall study group, along with trends for higher SDNN (standard deviation of the mean of sinus rhythm R-R intervals) and HFnu (normalised HF power), and for lower LFnu (normalised LF power). Additionally, a significant increase in BRS (from 2.2 ± 0.6 to 5.1 ± 2.2 ms/mm Hg, p = 0.01) was found in patients with baseline BRS ≤ 3 ms/mm Hg. A significant increase in rMSSD, pNN50, HF and HFnu, as well as a decrease in LFnu and LF/HF (LF to HF ratio) was observed in Group 1. In contrast, a significant increase in BRS was noted in Group 2. Various forms of 2-month physical training led to a favourable shift in autonomic balance towards parasympathetic activity. Our findings suggest a clinically important effect of physical activity in patients after AMI.

Central fatigue and sympathovagal imbalance during night shift in Japanese female nurses

The aim of this study was to examine the hypothesis that Japanese female nurses with a reduced total power (TP) component of heart rate variability (HRV) will show an imbalance in sympathovagal activity during night-time work. We carried out this study on 10 healthy female nurses (30.9 ± 3.1 years) working a night shift from 16:00 to 09:00. Heart rate (HR) and the different frequency power components of HRV were measured to estimate individual patterns of sympathovagal activity. A latent imbalance of sympathovagal activity was defined as higher HR and reduced TP, and subjects were divided into two groups based on TP values taken before the night shift. To evaluate central fatigue, we performed three different fatigue tests before and after night work in all subjects. Our results suggest that nurses with reduced HRV have an imbalance of sympathovagal activity but do not suffer from the effects of central fatigue.

Effects of Serum Calcium and Magnesium on Heart Rate Variability in Adult Women

The present study was designed to evaluate the association of serum calcium (Ca) and magnesium (Mg) levels with heart rate variability (HRV). One hundred and sixteen adult women were recruited in this cross-sectional study. Serum Ca and Mg levels were measured, and HRV in each time and frequency domain was recorded for 5min. Mean heart rate and standard deviation of the normal to normal interval (SDNN) and root mean square of differences of successive RR interval (RMSSD) in time domain and total power (TP), low-frequency power (LF), high-frequency power (HF), and LF/HF ratio in frequency domain were compared according to the tertiles of serum Ca and Mg levels and Ca/Mg ratio. The associations between serum Ca and Mg levels and Ca/Mg ratio with HRV were evaluated using regression analyses. Mean heart rate tended to increase from the lowest to the highest tertile of Ca levels (p = 0.081), whereas it decreased significantly with higher Mg levels (p = 0.026). Increasing SDNN value was observed from the lowest to the highest tertile of Mg levels (p = 0.009). SDNN value decreased significantly from the lowest to the highest tertile of Ca/Mg ratio (p = 0.030). Participants in the lowest tertile of Ca/Mg ratio had significantly higher TP and LF values compared to those in the middle and highest tertiles (p < 0.05). Decreasing SDNN, TP, and LF values were significantly associated with higher Ca/Mg ratios (p < 0.05). Associations of serum Mg level and Ca/Mg ratio with HRV could be one of the mechanisms involved in cardiovascular diseases.

The effect of rehabilitation on heart rate variability in patients with Parkinson's disease

Backround: Parkinson's disease includes disorders of the motor and autonomic functions (Oka et al., 2006). It is necessary to influence both systems to improve the health state of the patients. The effects of rehabilitation on the autonomic nervous system (ANS) are not clear yet. Objective: The aim of this study was to evaluate differences in the autonomic nervous system (ANS) regulation following a rehabilitation programme in patients with Parkinson's disease (PD) with the use of spectral analysis of heart rate variability (SAHRV) in a supine-standing-supine test. We wanted to compare findings in patients with PD prior to a rehabilitation programme with age-matched healthy controls. Methods: The group under study involved ten subjects (mean age 69.2 ± 5.9 years) with Parkinson's disease (9.2 ± 3.0 points according to the Webster scale), with a disease duration mean 3.3 ± 1.2 years. All patients used L-Dopa. We used the VarCor PF7 diagnostic system for the assesment of SAHRV. The findings in patients with PD before the rehabilitation programme were compared with those in a group of age-matched healthy subjects in a control group (n = 40; mean age 64.0 ± 7.4 years). Results: Significantly lower values of the LF (low frequency) and HF (high frequency) components were found in patients with PD in a repeated supine position, in comparison with those in a group of control subjects. The value of Total power in the same position was significantly lower in the group of patients with PD, too. Spectral parameter Power HF increased significantly and the Ratio LF/HF decreased significantly in patients with PD after rehabilitation programme. Conclusions: A decrease of the activity of the autonomic nervous system, which evidences disturbances of cardiovascular regulation, was found with the use of SAHRV in patients with PD. The value of the spectral parameter Power HF was significantly higher and the Ratio LF/HF was significantly lower in patients with PD after rehabilitation programme in comparison with their initial values. It could reflect positive changes in autonomic regulation in these patients.

Novel guess functions for efficient analysis of Raman fiber amplifiers

PurposeThe aim of the paper is to demonstrate a fast numerical solution for Raman fiber amplifier equations using proposed guess functions and MATLAB intrinsic properties. MATLAB BVP solvers are addressed for the solution.Design/methodology/approachThe guess functions proposed for the solution of RFA equations using MATLAB BVP solvers are derived from Taylor expansion of pump and signal wave near the boundary to specifically obtain convergence for the initial mesh point. The guess functions increase simulation speed significantly. In order to improve the simulation speed further, vectorization and analytical Jacobians are introduced. Comparisons among bvp4c and bvp5c have been made with respect to total pump power, number of signals, vectorization with/without analytical Jacobians, fiber length, relative tolerance and continuation method. The simulations are performed to determine the effect of the run time on the choice of the number of equally spaced mesh points (N) in the initial guess, and thus optimal N values are found.FindingsMATLAB BVP solvers have been proven to be effective for the numerical solution of RFAs with the proposed guess functions. In particular, with vectorizing, run time reduction is between 2.1 and 5.4 times for bvp4c and between 1.6 and 2.1 times for bvp5c and in addition to vectorizing, with the introduction of the analytical Jacobians, the reduction is between 2.4 and 6.2 times for bvp4c and 1.7 and 2.2 times for bvp5c, respectively, depending on the total pump power between 1,000 mW and 2,000 mW and the number of signals. Also, simulation results show that the efficiency of the solution with proposed guess functions is improved more than six times compared with those of previously reported continuation methods. Results show that the proposed guess functions with the vectorization and analytical Jacobians can be used for the performance evaluation of RFAs for the high power systems/long gain fiber span.Practical implicationsThe robust improvement of the solution proposed in this paper lies in the fact that the derived guess functions for the RFAs are highly effective in the sense that they assist the solver to converge to the solution for any total pump power value in a wide range from 1 to 3,000 mW and for any fiber lengths ranging 1 to 200 km which are used in practical applications. Hence, it is practicable for the performance evaluation of the existing RFA networks.Originality/valueThe novelty of this method is that, starting with the co‐propagating single pump and signal RFA schema, the authors derived the guess function specifically for the initial mesh points rather than using its analytical approximations. Moreover, the solution is generalized for co‐/counter propagating pumps/signals with the curve fitted coefficient(s).