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PubMed2006

Terahertz-laser control of large amplitude vibrational motion in the sub-one-cycle pulse limit.

We investigate the control of state-selective population transfer in the THz spectral range generated by sub-one-cycle pulse excitation. To this end we developed a zero-net-force modification of the optimal control algorithm which allows us to extend the algorithm into the ultrashort pulse domain. By combining the analysis of the control landscapes and that of optimal control theory, we were able to formulate a general mechanism suitable for laser control by ultrashort pulses. The strategy consists of a superposition of two pi-pulses with carrier envelope phases of phi = pi/2. The first pulse is effectively in resonance with the targeted transition, while the second one, fired at around the minimum of the first pulse second lobe, removes leaking to the dipole-coupled background state. To compensate for the pulses ultrashort duration, the carrier frequencies of both pulses are red-shifted from the spectroscopic resonance.

Journal Article↗
PubMed2000

A prototype device for standardized calibration of pulse oximeters.

OBJECTIVE: To develop and test a method for standardized calibration of pulse oximeters. METHODS: A novel pulse oximeter calibration technique capable of simulating the behavior of real patients is discussed. It is based on an artificial finger with a variable spectral-resolved light attenuator in conjunction with an extensive clinical database of time-resolved optical transmission spectra of patients fingers in the wavelength range 600-1000 nm. The arterial oxygen saturation of the patients at the time of recording was derived by analyzing a corresponding blood sample with a CO-oximeter. These spectra are used to compute the modulation of the light attenuator which is attached to the artificial finger. This calibration method was tested by arbitrarily playing back recorded spectra to pulse oximeters and comparing their display to the value they displayed when the spectra were recorded. RESULTS: We were able to demonstrate that the calibrator could generate physiological signals which are accepted by a pulse oximeter. We also present some experience of playing back recorded patient spectra. The mean difference between the original reading of the pulse oximeters and the display when attached to the calibrator is 1.2 saturation points (displayed oxygen saturation SpO2) with a standard deviation of 1.9 saturation points. CONCLUSIONS: The tests have shown the capabilities of a spectral light modulator for use as a possible calibration standard for pulse oximeters. If some improvements of the current prototype can be achieved we conclude from the experience with the device that this novel concept for the calibration of pulse oximeters is feasible and that it could become an important tool for assessing the performance of pulse oximeters.

Calibration↗
PubMed2001

Characteristics of the pulse waveform during altered nitric oxide synthesis in the rabbit.

Nitrovasodilators produce characteristic changes in the shape of the peripheral pulse wave. Similar changes might also be caused by alteration of endogenous NO activity, which would allow such activity to be assessed in vivo. We investigated whether manipulation of the NO pathway influences the pulse waveform, and the mechanisms involved. The pulse wave in the ear of normal rabbits was examined by reflectance photoplethysmography before and during infusion of vasoactive agents. Pulse wave velocity was assessed by using an additional sensor on the rear foot. A diastolic peak was observed in the ear pulse; its timing was consistent with it being a reflection of the systolic peak from the lower body. The height of the dicrotic notch marking the start of this diastolic wave was decreased by acetylcholine or an NO donor, and further decreased by a phosphodiesterase type V inhibitor. The acetylcholine-induced decreases were blocked by inhibiting NO synthesis with N(G)-nitro-L-arginine methyl ester (L-NAME) but were unaffected by the inactive enantiomer D-NAME. These data demonstrate that NO influences the height of the notch in the pulse wave. Heart rate and blood pressure were altered during acetylcholine or L-NAME infusion, but there were no changes in pulse wave amplitude or velocity, or in the timing of the diastolic peak or dicrotic notch. The slope of the pulse wave between the systolic peak and notch changed substantially. These effects are most convincingly explained by changes in wave reflection, not only from the lower body but also from more proximal sites.

Acetylcholine↗
PubMed2002

Flashlamp pulsed dye laser and argon-pumped dye laser in the treatment of port-wine stains: a clinical and histological comparison.

BACKGROUND: Port-wine stains (PWS) are congenital vascular malformations occurring in 0.3% of children. The pulsed dye laser is a well established treatment for PWS. OBJECTIVES: To compare, clinically and histologically, the effects of the flashlamp pulsed dye laser with the argon-pumped dye laser in the treatment of PWS. METHODS: Thirty patients were treated on two to four test areas with both laser types using different energy fluences. A flashlamp pulsed dye laser with 0.45 ms pulse duration and a spot size of 5 mm was compared with an argon-pumped dye laser, with a spot size of 1 mm delivered with a robotic scanning laser handpiece (Hexascan) and 70-190 ms pulse duration. Both were tuned to 585 nm. Twelve weeks later the degree of lightening was evaluated and biopsies were taken. To count the vessels the skin sections were stained with CD34 using an immunohistochemical technique. The vessels were divided into three groups by diameter (d): d < 10 microm, 10 < or = d < 20 microm, d > or = 20 microm. RESULTS: The clinical results showed a significantly better lightening using the flashlamp pulsed dye laser than with the argon-pumped dye laser. The histological results showed a significant decrease in the number of vessels of diameter larger than 20 microm in treated compared with untreated lesions. We found no histological difference in the number of vessels between the two laser treatments. However, there was a tendency towards more small vessels (diameter < 10 microm) after one treatment with the flashlamp pulsed dye laser compared with untreated PWS. CONCLUSIONS: The flashlamp pulsed dye laser is clinically superior to the argon-pumped dye laser in the treatment of PWS.

Adolescent↗
PubMed1998

Maternal perceptions of labor with fetal monitoring by pulse oximetry in a research setting.

OBJECTIVE: Little research has evaluated maternal experience with fetal pulse oximetry for fetal surveillance. The purpose of this study was to compare maternal perceptions of labor with intrapartal cardiotocography with or without fetal pulse oximetry in a research setting. METHODS: One hundred women with vaginal, vertex deliveries and uncomplicated fetal outcomes were enrolled. The study group was a subset of 50 mothers who had participated in a pulse oximetry trial. The control group of 50 mothers was monitored by cardiotocography only. Both groups were matched for age, parity, weeks of gestation, epidural anesthesia use, and duration of labor. A global measure of maternal perception of labor was established by experience with labor, general attitude toward monitoring devices, satisfaction with monitoring, nursing and medical care, and anxiety, each of which was evaluated separately. The mothers in the study group were also interviewed about aspects related to the fetal pulse oximetry research setting, such as information, movement restriction, discomfort, care, privacy, and safety. The questionnaires were based on a standardized rating scale model, and the interviews were conducted two to four days after delivery. The results were analyzed by chi-squared, paired t test, and ANOVA. RESULTS: No significant differences were observed between the study and control participants in any parameter concerning the maternal perception of labor. Mothers' experiences with pulse oximetry as assessed by interview was overwhelmingly positive. CONCLUSIONS: Fetal monitoring by pulse oximetry in a research setting did not affect maternal perceptions of labor. Mothers' experiences with pulse oximetry were highly positive, suggesting that research in fetal pulse oximetry need not compromise maternal perceptions of labor.

Adult↗
PubMed2001

Resurfacing of pitted facial acne scars with a long-pulsed Er:YAG laser.

BACKGROUND: Conventional short-pulsed Er:YAG lasers show less effective hemostasis and weak photothermal damage on papillary dermis. Recently, newer long-pulsed Er:YAG laser systems has been developed. OBJECTIVE: To evaluate the clinical and histologic effects of long-pulsed Er:YAG laser resurfacing for pitted facial acne scars. METHODS: Thirty-five patients with pitted facial acne scars were treated with a long-pulsed Er:YAG laser. All patients had Fitzpatrick skin phototypes III-V. A pulsed Er:YAG laser with a 5 mm handpiece at a setting of 7.0-7.5 J/cm2 with a 10-msec pulse duration was used. The laser was fired at 5 Hz, with four to five passes. In 28 patients, the results of laser treatment were evaluated for the degree of clinical improvement, duration of erythema, pigmentary change, and any adverse events at 2 weeks, 1 month, and 3 months. In seven patients, skin biopsy specimens were obtained at the following intervals: immediately, 1 week, 2 weeks, 4 weeks, and 8 weeks postoperatively for histologic examination. RESULTS: The results of long-pulsed Er:YAG laser resurfacing for pitted facial acne scars were excellent in 10 patients (36%), good in 16 patients (57%), and fair in 2 patients (7%). Erythema occurred in all patients after laser treatment and lasted longer than 3 months in 15 patients (54%). Postinflammatory hyperpigmentation occurred in 8 patients (29%). But the pigmentation faded or disappeared within 3 months. One patient (4%) experienced mild hypopigmentation. Pruritic symptoms that required medical intervention occurred in 16 patients (57%). Mild to moderate postoperative acne flare-up occurred in 8 patients (29%). No other adverse effects such as scarring, bacterial infection, or contact dermatitis were observed. CONCLUSION: In conclusion, resurfacing with a long-pulsed Er:YAG laser is a safe and very effective treatment modality for pitted facial acne scars.

Acne Vulgaris↗
PubMed2002

Evaluation of a new super-long-pulsed 810 nm diode laser for the removal of unwanted hair: the concept of thermal damage time.

BACKGROUND: Laser hair removal is based on the dual concepts of selective photothermolysis and thermal relaxation time. In most laser hair removal systems, light with emitted pulse durations of 2-50 msec targets hair follicles. A novel concept of laser hair removal uses the thermal damage time rather than the thermal relaxation time of the hair follicle. The follicle's thermal damage time is the amount of time required for diffusion of delivered laser energy from the treated hair to follicular-associated hair stem cells. This can range from 170 to 1000 msec. OBJECTIVE: To investigate the theory of thermal damage time, we performed a pilot study to evaluate the clinical efficacy and side effect profile of a modified 810 nm diode laser device operating in a super-long-pulse mode (200-1000 msec). METHODS: Ten female subjects with Fitzpatrick skin types I-VI received either one or two laser treatments at eight test sites. Super-long pulse durations of 200-1000 msec were evaluated with delivered fluences ranging from 23 to 115 J/cm2. Subjects were followed for 6 months after the first treatment. Subjects were evaluated for hair removal efficiency, optimal pulse duration and delivered fluence, and associated complication rate. RESULTS: The clinical results show that safe hair removal in all skin types can be accomplished with an 810 nm diode laser delivering super-long pulse durations. Pain and complications were greatest at the highest pulse duration (1000 msec) and the highest fluence (115 J/cm2). Optimal hair reduction at 6 months (31%) was achieved at a thermal diffusion time of 400 msec (46 J/cm2). CONCLUSION: The super-long pulsed 810 nm diode laser can safely remove unwanted hair in a full variety of skin types. Pain and increased risk of complications may preclude the use of the laser at very high fluences and pulse duration in the range of 1000 msec.

Adult↗
PubMed2003

Clinically significant facial edema after extensive treatment with purpura-free pulsed-dye laser.

BACKGROUND: Long-pulsed pulsed-dye lasers permit treatment of facial erythema and telangiectasia with purpura-free technique, which may be more comfortable for the patient than purpura-inducing treatment. However, there are anecdotal reports of treatment-associated discomfort even when purpura is not elicited. OBJECTIVE: To determine whether patients experience clinically significant erythema, edema, and pain after purpura-free treatment with pulsed-dye laser. METHODS: In this prospective, controlled study, subjects included 15 patients who were undergoing purpura-free treatment of diffuse erythema and fine telangiectasia of at least half the facial surface area with purpura-free pulsed-dye, and it included 15 age, gender, and skin-type matched control subjects who were undergoing similar treatments but with the induction of trace to mild purpura. Patients were seen in person and were surveyed by phone regarding symptoms and signs during their postoperative courses. RESULTS: Postoperative erythema of a mean 3.3-days duration and 3.4/5.0 intensity was reported by 73% (11 of 15) of the purpura-free patients. Among purpura patients, the duration was 5.6 days. The intensity was 4.0, and again, 73% of patients reported this finding. Postoperative edema occurred among 87% of purpura-free patients, but such edema occurred in all of the purpura patients, in whom it lasted longer and was more intense. Symptomatic eye swelling and uncomfortable/painful edema were seen in 27% and 20%, respectively, of purpura-free patients, but in 40% and 53% of purpura patients. Among purpura-free patients receiving fewer than 250 laser pulses per treatment, erythema and edema lasted less than 1 day and 2.5 days, whereas the mean durations were 3.4 and 5.0 days for purpura-free patients receiving greater than 250 pulses. CONCLUSION: Extensive purpura-free treatment for erythema and telangiectasia of the face with the long-pulsed pulsed-dye laser can lead to clinically significant erythema, edema, and discomfort in patients. The duration, magnitude, and frequency of these undesired effects are markedly less with purpura-free treatment compared with purpura-inducing treatment and are also less for less extensive purpura-free treatments.

Edema↗
PubMed2003

Gastric electrical stimulation with short pulses reduces vomiting but not dysrhythmias in dogs.

BACKGROUND & AIMS: The aim of this study was to investigate the acute effects of 3 different methods of electrical stimulation in the prevention of vasopressin-induced emetic response and gastric dysrhythmias. METHODS: Seven female hound dogs chronically implanted with 4 pairs of electrodes on gastric serosa were used in a 5-session study. Saline and vasopressin were infused in sessions 1 and 2, respectively. In the other 3 sessions with vasopressin infusion, 3 different methods of electrical stimulation (short-pulse stimulation, long-pulse stimulation, and electroacupuncture) were applied. Gastric slow waves and vomiting and behaviors suggestive of nausea were recorded in each session. In a separate study, additional experiments were performed in 5 vagotomized dogs to investigate vagally mediated mechanisms. RESULTS: Vasopressin induced gastric dysrhythmias, uncoupling of slow waves, and vomiting and behaviors suggestive of nausea (P < 0.02, analysis of variance). Long-pulse stimulation, but not short-pulse stimulation or electroacupuncture, was capable of preventing vasopressin-induced gastric dysrhythmias and gastric slow wave uncoupling. Short-pulse stimulation and electroacupuncture, but not long-pulse stimulation, prevented vomiting and significantly reduced the symptom scores, which was not noted in the dogs with truncal vagotomy. CONCLUSIONS: Long-pulse stimulation normalizes vasopressin-induced slow wave abnormalities with no improvement in vomiting and behaviors suggestive of nausea. Short-pulse stimulation and electroacupuncture prevent vomiting and behaviors suggestive of nausea induced by vasopressin but have no effects on slow waves, and their effects are vagally mediated.

Animals↗
PubMed1996

[Initial experiences with pulsed fluoroscopy on a multifunctional fluoroscopic unit].

PURPOSE: Comparison of radiation doses in pulsed and continuous fluoroscopy to quantify the dose reduction by pulsed fluoroscopy. Further, the applicability of pulsed fluoroscopy in clinical routine has been evaluated. MATERIALS AND METHODS: In a human pelvic phantom, the radiation dose (skin entry dose in cGycm2) was measured at two pulses per second (pps), 3 pps, 6 pps, 12 pps and continuous fluoroscopy mode, respectively, using image-intensifier entries of 38 cm, 25 cm, and 17 cm. 300 examinations were carried out, and the results of the different fluoroscopy modes were registered. RESULTS: Dose reduction depends on the image-intensifier entry. Compared to the radiation dose in continuous fluoroscopy, with 12 pps fluoroscopy the radiation dose can be reduced at a minimum of 51%, with 6 pps fluoroscopy to 40%, with 3 pps fluoroscopy to 20%, and with 2 pps fluoroscopy to a minimum of 14.5%. Clinical routine has shown that 78% of all examinations can be performed with 2 or 3 pps fluoroscopy mode. In 12.7% of the cases pulsed fluoroscopy of diverse frequencies was used, in an additional 2% combined with continuous fluoroscopy. Exclusively, continuous fluoroscopy has been employed in 2% of the cases. CONCLUSIONS: Using pulsed fluoroscopy, an 80% reduction of the radiation dose compared to continuous fluoroscopy is possible. About 96% of all examinations can be performed with pulsed fluoroscopy of different pulse rate and without using continuous fluoroscopy.

Diagnostic Tests, Routine↗
PubMed2004

Optical control of two-photon excitation efficiency of alpha-perylene crystal by pulse shaping.

Optimized pulse shaping experiments were carried out on the control of two-photon excitation efficiency of an alpha-perylene crystal in the temperature region from 30 to 290 K. It was found that a pulse train with a pulse interval of 90 fs and an alternately reversing phase relation increased the excitation efficiency by a factor of 2 for the whole temperature region. The pulse shape characteristic for effective efficiency increase was reduced by double pulse experiments in which the dependence of the emission intensity on the pulse interval and relative phase between pulses were measured. The mechanism of the efficiency increase is briefly discussed using a sliding-window Fourier transform of the pulse shape.

Journal Article↗
PubMed2006

Pulse shaping effect on two-photon excitation efficiency of alpha-perylene crystals and perylene in chloroform solution.

We demonstrated that the two-photon excitation efficiency of perylene in chloroform solution as well as that of crystalline perylene was dramatically increased by optimizing the shape of intense femtosecond laser pulses of a regenerative amplifier output. The efficiency was three times higher than for an unshaped single femtosecond pulse with the pulse width of shorter than 50 fs. The pulse shape optimized for the solution sample was a pulse train with a repetition frequency of about 340 cm(-1), and the pulse shape optimized for crystalline perylene was very similar. These results supported our previous findings on alpha-perylene crystals using weak femtosecond pulses from a mode-locked laser oscillator [T. Okada et al. J. Chem. Phys. 121, 6385 (2004)]. Furthermore, it was confirmed that the shaped pulse optimized for the liquid sample could also increase the two-photon excitation efficiency of alpha-perylene crystals and vice versa. We concluded that the mechanism for the increase in excitation efficiency of perylene in chloroform was almost the same as that for alpha-perylene crystal, and that the efficiency increased mainly through intramolecular dynamical processes. Processes involving intermolecular interactions and/or energy states delocalized over the crystal cannot play the major role.

Journal Article↗
PubMed1985

Ca2+ entry in squid axons during voltage-clamp pulses is mainly Na+/Ca2+ exchange.

Intact squid axons were injected with aequorin and bathed in 3 mM Ca seawater (a concentration close to that of squid blood). Sodium and potassium currents were pharmacologically blocked and repetitive voltage-clamp pulses of a duration of 1.5 ms were applied (to simulate the duration of an action potential) at amplitudes of +30 to +90 mV and at frequencies of 100/s. In a very fresh axon (low internal Na concentration) no detectable change in aequorin glow resulted from this treatment, whether the axons were in Na-containing or in Na-free seawater. In axons subjected to modest Na loading, repetitive voltage-clamp pulsing did not result in an increased aequorin glow when the pulses were delivered in Na seawater, whereas in Na-free seawater there was an easily measurable increase in aequorin light emission during repetitive pulsing. The increase in aequorin photons emitted per voltage-clamp pulse was e-fold for 22 mV of depolarization, and the process showed no signs of saturating at pulse amplitudes of +180 mV (i.e., at a membrane potential close to ECa). The aequorin light emission per voltage-clamp pulse increased linearly with pulse duration (at constant amplitude).

Action Potentials↗
PubMed2004

Combination therapy consisting of week pulses of oral terbinafine plus topical application of terbinafine cream in the treatment of onychomycosis.

BACKGROUND: Terbinafine, based on its pharmacokinetic properties, is a good candidate for pulse therapy. There are, as yet, no current guidelines for a terbinafine 1-week pulse regimine. OBJECTIVE: To determine the optimal 1-week pulse dosing regimen for combination therapy of oral terbinafine with complementary 1% terbinafine cream for the treatment of onychomycosis. DESIGN: A total of 69 onychomycosis patients received 250 mg terbinafine, given orally once daily for 7 days as 1-week pulses, separated by intervals of 2-3 weeks, until the desired improvement was observed. A daily application of 1% terbinafine cream was advised through to the evaluation date at 12 months follow-up. The treatment regimens were compared based on the number of pulses and the duration of treatment. RESULTS: The 45 patients (65.2%) who achieved complete cure received an average of 7.8+/-3.5 pulse treatments over 4.8+/-2.6 months. The optimal terbinafine dosing regimen consisted of alternate 1-week pulses, with most patients on this regimen (19/20 cases; 95%) achieving total cure. CONCLUSION: Favorable treatment outcome was gained from this terbinafine 1-week pulse regimen and also better compliance compared with a standard daily regimen.

Administration, Oral↗
PubMed1986

Chemical reactions by pulsed ultrasound: memory effects in the formation of NO3- and NO2- in aerated water.

The formation of nitrate and nitrite in the sonolysis of aerated water was studied using pulses of 300 kHz ultrasound. At very low on/off ratios, the yield decreases with decreasing pulse duration. At a pulse length of 3 X 10(-3) s, the yield is zero. This time is identified as the 'activation' time tau 1 of small gas bubbles formed by cavitation. At larger on/off ratios, a pulse is more effective the shorter the time interval between the pulses. This memory effect is described by a 'deactivation' time tau 2 of the system, which amounts to about 6 X 10(-2) s. At large on/off ratios (1:3 and 1:1) the yield never becomes zero. It first decreases with decreasing pulse length (increasing modulation frequency) and increases again for very short pulses. The results are also discussed with respect to the use of pulsed ultrasound in diagnostic applications.

Air↗
PubMed2005

The use of pulsed ultrasound technology to improve environmental remediation: a comparative study.

Relatively little is known about the effects of pulsed ultrasound on the facilitation of chemical reactivity and remediation. Previous studies have indicated that sonochemistry using pulses may be either more or less effective than continuous wave (CW) ultrasonic irradiation. However, because of the time-modulated nature of the pulses used in these studies, less acoustic energy in general was transmitted to the solutions compared to CW sonication. The effectiveness of ultrasound when the pulse is adjusted so that the same amount of acoustic energy is input compared to continuous irradiation over a given time has not been previously explored. In this study we have embarked on a comparison of the efficacy of power-modulated pulsed (PMP) sonochemistry with more traditional time-modulated pulsing. As a prototypical reaction, we have explored the effects of pulse type on the degradation of acid orange, a common industrial colorant. An increase in the degradation rate by a factor of three was observed using PMP ultrasound compared with continuous irradiation under conditions of equivalent acoustic input power, while the use of time-modulated pulsed ultrasound from a commercially available direct-immersion (DI) horn-type sonicator exhibited a rate decrease compared to CW sonication. Possible mechanisms for the enhancement are discussed.

Azo Compounds↗
PubMed2001

Evaluation of a super long pulsed 810-nm diode hair removal laser in suntanned individuals.

BACKGROUND: Laser hair removal is based on the dual concepts of selective photothermolysis and thermal relaxation time. In most laser hair removal systems, light with emitted pulse durations of 2-50 ms targets hair follicles. Such pulse durations usually lead to post-inflammatory pigmentary changes in suntanned individuals. OBJECTIVE: In this pilot study, we evaluated the clinical efficacy and side effect profile of a modified 810-nm diode laser device (Palomar SLP 1000, Burlington, MA, USA) operating in a super long pulse mode (200-1000 ms). METHODS: Five suntanned subjects with Fitzpatrick skin types II-IV received either one or two laser treatments at eight test sites. Treatments were delivered to suntanned skin. Pulse durations of 200-1000 ms were evaluated with delivered fluences ranging from 23 to 115 J/cm(2). Subjects were followed for 6 months after the first treatment. Subjects were evaluated for hair removal efficiency, optimal pulse duration and delivered fluence, one versus two treatments, and associated complication rate. RESULTS: The average hair reduction, 34%, did not significantly vary with pulse duration or fluence. Clinical evaluations rated two treatments superior to one. CONCLUSION: The results show that efficacious and safe hair removal can be accomplished with an 810-nm diode laser delivering super long pulse durations at a wide range of settings in suntanned individuals. For optimal safety in tanned patients, the highest fluence (115 J/cm(2)) and pulse duration (1000 ms) should be avoided.

Adult↗
PubMed2001

Phase-shifting effects of dusklike and dawnlike light pulses on the circadian activity rhythms of Syrian hamsters.

This study tested whether light pulses with a dusklike offset or a dawnlike onset caused phase shifts of different sizes in the circadian wheel-running activity of Syrian hamsters, Mesocricetus auratus. Six experiments were conducted, each with 30 hamsters; the hamsters received first one type of pulse and then the other type a few weeks later, allowing a paired comparison. The six experiments represented the combination of two maximum light intensities (150 and 250 lux) and three zeitgeber times (ZTs) at which the pulses were given (ZT13.5, ZT14.5, and ZT20). Pulses were 30 minutes long, a relatively short duration to minimize circadian time effects. Aschoff's type II method of measuring phase shifts was used. In none of the six experiments did a two-tailed paired t test detect a significant difference in the size of phase shifts caused by dusklike versus dawnlike pulses. A three-way analysis of variance (ANOVA) on the combined data from all six experiments (with pulse type, pulse intensity, and ZT as factors) also failed to detect a significant effect of pulse type. Statistical power was calculated and found to be reasonably good. These negative results are in line with those of a previous study in which a different methodology was used.

Analysis of Variance↗