Green Pulses Research Articles

Green pulse regenerative amplification using a Pr3+:LiYF4 crystal pumped by GaN blue laser diodes.

Direct regenerative amplifications of green pulses (522 nm) were investigated using a Pr3+-doped LiYF4 crystal pumped by GaN blue laser diodes. Green pulses with two different temporal duration regimes, i.e. sub-picosecond (sub-ps) and sub-nanosecond (sub-ns), were prepared from the second harmonic generation of the mode-locked Yb3+-doped fiber laser at the repetition rate of 100.86 kHz and used as a seed for the comparison of the amplification processes. For the sub-ps (0.63 ps) and sub-ns (0.3-0.4 ns) seeds, the amplifications resulted in 1.25 µJ and 1.53 µJ in the pulse energies, 0.60 nm and 0.27 nm bandwidths, and the beam qualities of (M2x = 2.26, M2y = 1.25) and (M2x = 1.47, M2y = 1.23), respectively. A comparison of the B integrals confirmed that the wider bandwidth and the lower beam quality of the sub-ps seed amplification versus the sub-ns seed amplification were caused by the nonlinear effects in the sub-ps amplification.

Localized surface plasmon resonance induced nonlinear absorption and optical limiting activity of gold decorated graphene/MoS2 hybrid

The synergistic supremacy of a hybrid nanocomposite made of reduced graphene oxide (rGO), molybdenum disulfide (MoS2) and gold nanoparticles (Au) for Q-switching and optical limiting applications is investigated. Hydrothermally synthesized Au-rGO-MoS2 hybrid with varying concentrations of Au (2.5, 5, 7.5 and 10 wt%) was subjected to interact with Q-switched Nd:YAG nanosecond green laser pulses. The intensity dependent nonlinear absorption studies revealed a switch over in the nonlinear behaviour from saturable absorption (SA) to reverse saturable absorption (RSA) behaviour. SA occurs due to ground state bleaching at comparatively lower laser irradiances serving the need for Q-switching and optical communications. The RSA trait at higher laser irradiance is attributed to sequential two-photon absorption which serves as the platform for optical limiting behaviour prompting laser safety and effective photothermal therapy applications. The strong mid-visible and UV absorption promotes the availability of multiple energy bands for energy transitions of excited state absorption (ESA). Enhanced local fields due to localized surface plasmon resonance effect, structural defects, hierarchical morphology, increased absorption cross-section and plasmon induced energy transfer promotes robust ESA process. These tunable nonlinear optical properties make Au-rGO-MoS2 hybrid promising futuristic candidates for applications in nonlinear photonic devices, ultrafast optical switches and all-optical signal processing systems.

A Combination of Remote Sensing Datasets for Coastal Marine Habitat Mapping Using Random Forest Algorithm in Pistolet Bay, Canada

Marine ecosystems serve as vital indicators of biodiversity, providing habitats for diverse flora and fauna. Canada’s extensive coastal regions encompass a rich range of marine habitats, necessitating accurate mapping techniques utilizing advanced technologies, such as remote sensing (RS). This study focused on a study area in Pistolet Bay in Newfoundland and Labrador (NL), Canada, with an area of approximately 170 km2 and depths varying between 0 and −28 m. Considering the relatively large coverage and shallow depths of water of the study area, it was decided to use airborne bathymetric Light Detection and Ranging (LiDAR) data, which used green laser pulses, to map the marine habitats in this region. Along with this LiDAR data, Remotely Operated Vehicle (ROV) footage, high-resolution multispectral drone imagery, true color Google Earth (GE) imagery, and shoreline survey data were also collected. These datasets were preprocessed and categorized into five classes of Eelgrass, Rockweed, Kelp, Other vegetation, and Non-Vegetation. A marine habitat map of the study area was generated using the features extracted from LiDAR data, such as intensity, depth, slope, and canopy height, using an object-based Random Forest (RF) algorithm. Despite multiple challenges, the resulting habitat map exhibited a commendable classification accuracy of 89%. This underscores the efficacy of the developed Artificial Intelligence (AI) model for future marine habitat mapping endeavors across the country.

Effect of Prebiotic Rich Diet on Gut Microbiome in Patients (Pts) Undergoing Stem Cell Transplants- Results of Phase I Study (NCT04629430)- Clinical Outcomes

Introduction An increase in gut microbial diversity during Stem cell transplant (HSCT) has been associated with improved treatment-related mortality (TRM) and gastro-intestinal graft versus host disease (GI GVHD). Prebiotics are indigestible carbohydrates rich in fructo-oligosaccharides such as inulin and Galacto- oligosaccharides. Prebiotics are metabolized by the gut bacteria to produce short-chain fatty acids which in turn nourish the gastrointestinal- epithelium. Hence, the implementation of a diet rich in pre-biotics could increase gut microbial diversity and improve outcomes such as GVHD and Overall survival (OS). We report clinical results from single-center Phase I study that investigates the feasibility of consuming a prebiotic rich diet in patients undergoing HSCT. Methods Both Allogeneic (Allo) and Autologous (Auto) HSCT Pts >18 yrs were included. Allo Pts undergoing second transplants and needing broad-spectrum antibiotics 1 week before starting the conditioning regimen were excluded. Pts were requested to have at least 2 servings of prebiotic-rich foods such as oats, artichokes an greens daily from the date of conditioning HSCT chemotherapy to Day +100. A list of vegetables and grains with serving size of approximately 5 grams of commercially available fructo-oligosaccharides per day was provided and consumption was recorded with a patient-reported diary. Stool samples were collected before the start of HSCT conditioning regimen, and once a month for 3 months post-transplant. Compliance was defined as consuming 2 servings of prebiotics >/= 80% days of the study period. Secondary endpoints included incidence of acute GVHD, Clostridium difficle infections (C.Diff), Neutrophil (ANC), and Platelet Engraftment. Exploratory endpoints included Meta- genomics sequencing of the stool samples and patient-reported quality of life (QoL) outcomes. Results 27 Pts, median age 60 yrs were enrolled in this phase 1 study. 5 patients withdrew prior to Day 100 of the intervention. Difficulty in following the diet and maintaining the diary were cited as the main reasons for the withdrawal. 14 were female; 14 pts had Allo HSCT, 5 of whom had Myeloablative conditioning. Only 8 pts were able to comply with the diet (29.6%), 19 were not compliant - of whom 11 (40.8%) pts were not able to comply with the diet and 8 patients were not able to provide a diary. Attempts were made to communicate with them to get an approximation of consumption, none reported > 80% of the study period. None of the patients had C diff infections, 3 of 14 Pts developed acute skin GVHD, grade 1-2; no GI GVHD was reported. Day 100 overall Survival was 100% for both Auto and Allo transplant pts. 1 yr OS 25 pts were evaluable and was 100% and 85.8% in the Auto and Allo Group respectively. 1 pt died of relapsed disease, and another of uncontrolled sepsis at Day +360, after cessation of the diet. Median days for ANC engraftment, and platelet engraftment in the Auto group were 10 days and 16 days; in the Allo group were 17 days and 18 days respectively. The mean percent of change in weight from pre-conditioning to day +100 was -10.26% in the Allo group and -2.5% in the Auto group. FACT-BMT QOL total score decreased by a mean percent of 10.7 % in the Allo pts and improved by 3.8% in the Auto group at Day 100 after transplant from baseline. Meta-genomic analysis of stool samples is currently ongoing. Conclusion Results from the Phase I study unfortunately show that a naturally occurring prebiotic-rich diet of green leafy vegetables, pulses, and fiber-rich food is very hard to consume daily in the first 100 days after HSCT. Regional dietary habits, mucositis, and chemotherapy-related change in taste could be contributory factors. However, most importantly implementation of this diet did not result in adverse events such as increased sepsis, GI GVHD, or C Diff infections and reported a remarkable 1 yr OS. Hence further studies to help improve compliance of diet with foods rich in pre-biotics may have a valuable impact on post-Transplant outcomes.

Effects of fermented banana pseudo-stem sap (Musa acuminata L.) on the growth and yield attributing characters of marigold variety Karma 555-Orange

The high cost of marigold production through the application of synthetic fertilizers and micronutrients is a major concern for Nepalese farmers. Every year, the nutrient-rich banana pseudo-stems are wasted after harvest. Utilizing the banana’s pseudo-stem for increasing marigold productivity through sustainable agricultural practices, an experiment was conducted to determine the optimum concentration of banana pseudo-stem sap (BPS) to be applied by foliar spraying to marigold variety (Karma 555 – Orange). The BPS was mixed and enriched with different ingredients, such as cow urine, cow dung, neem leaf, green gram leaf, pulse flour, vermin-liquor, jaggery, and fermented curd. The mixture was incubated under anaerobic conditions before applying the foliar spray. The study was carried out in a completely randomized block design, with three replications and seven treatments. The treatments were 0.5 % BPS, 1 % BPS, 2 % BPS, 3 % BPS, 4 % BPS, 5 % BPS, and the control. Data were recorded at 50, 70, and 90 days after transplantation (DAT). Among the treatments, the 3 % BPS solution showed significant effects on most of the growth parameters: plant height (85.07 cm), plant spread (63.47 cm) at 5% level at 90 DAT, and yield attributes such as the number of flowers per plant (74.00) at 5% level, individual flower weight (8.10 g), individual flower diameter (7.55 cm), and flower yield (597.25 g plant-1) at 1% level of significance respectively. It was found that growth and yield attributes increased with increasing concentrations of BPS up to 3 % and decreased thereafter. According to the results, foliar spray of marigold with 3 % BPS (enriched solution) resulted in the highest yield and yield components of marigold in the Chitwan area which could be an effective alternative to synthetic hormones for enhancing the growth and quality of marigolds under field conditions.

Generation of Joule-level green bursts of nanosecond pulses from a DPSSL amplifier.

A new approach to generation of a burst of high-energy green pulses by placing a high-energy multi-slab Yb:YAG DPSSL amplifier and SHG crystal inside a regenerative cavity is presented. In a proof-of-concept test, stable generation of a burst of six green (515 nm) pulses, each 10 ns in duration and separated by 29.4 ns (34 MHz), with 2.0 J total energy has been demonstrated at 1 Hz from a non-optimized ring cavity design. A maximum individual green pulse energy of 580 mJ was produced from a 1.78 J circulating infrared (1030 nm) pulse (average fluence 0.9 J/cm2), corresponding to a SHG conversion efficiency of 32%. Experimental results have been compared with predicted performance from a simple model. Efficient generation of a burst of high energy green pulses offers an attractive pump source for Ti:Sa amplifiers, providing the potential to reduce the impact of amplified stimulated emission by reducing instantaneous transverse gain.

Thermographic 3D particle tracking velocimetry for turbulent gas flows

Turbulent flows are characterized by diverse and unsteady three-dimensional (3D) features that require 3D measurements to study. In case of non-isothermal flows, combined 3D measurements of temperature and velocity are necessary. In this paper, a thermographic 3D particle tracking velocimetry (thermographic 3D-PTV) concept is introduced for simultaneous 3D temperature and velocity measurements in turbulent gas flows. It is based on sub-micron thermographic phosphor particles seeded into the flow as flow tracers with low response times of a few microseconds. To obtain each tracer’s position and velocity, the measurement region is illuminated volumetrically using a double-pulse green laser and Mie-scattered light is imaged by four double-frame cameras. Following the pinhole model-based calibration of all cameras, 3D particle positions are computed for both laser pulse-times using a fast minimum line of sight reconstruction code. Three-component velocities are derived from tracking individual particles between these time steps. For simultaneous 3D thermometry, temperature dependent luminescence emissions from the same phosphor particles are exploited. These emissions are excited using a UV laser synchronized with the first green laser pulse and imaged using two cameras equipped with spectral filters for ratiometric phosphor thermometry. As a result, instantaneous 3D fields of discrete temperature and velocity measurements are obtained throughout the volume. The concept is demonstrated in a turbulent heated gas jet emerging from a circular nozzle at a particle image concentration of 0.005 particle per pixel, where the symmetry of the velocity and temperature distributions about the jet axis is successfully reconstructed.

Direct generation of 3.17 mJ green pulses in a cavity-dumped Ho3+-doped fiber laser at 543 nm

High-energy pulsed lasers in the green spectral region are of tremendous interest for applications in space laser ranging, underwater detection, precise processing, and scientific research. Semiconductor pulsed lasers currently are difficult to access to the so-called “green gap,” and high-energy green pulsed lasers still heavily rely on the nonlinear frequency conversion of near-IR lasers, precluding compact and low-cost green laser systems. Here, we address this challenge by demonstrating, for the first time to the best of our knowledge, millijoule-level green pulses generated directly from a fiber laser. The green pulsed fiber laser consists of a 450 nm pump laser diode, a Ho3+-doped ZBLAN fiber, and a cavity-dumping module based on a visible wavelength acousto-optic modulator. Stable pulse operation in the cavity-dumping regime at 543 nm is observed with a tunable repetition rate in a large range of 100 Hz–3 MHz and a pulse duration of 72–116 ns. The maximum pulse energy of 3.17 mJ at 100 Hz is successfully achieved, which is three orders of magnitude higher than those of the rare-earth-doped fiber green lasers previously reported. This work provides a model for compact, high-efficiency, and high-energy visible fiber pulsed lasers.

Multipass cell post-compression at 515 nm as an efficient driver for a table-top 13.5 nm source

We present a table-top, efficient and power scalable scheme enabling the effective generation of extreme ultraviolet radiation up to 100 eV photon energy. Therefor ultrashort pulses (< 20fs) in the visible spectral range (515 nm) are used to drive high harmonic generation (HHG) in helium. This allows for a significant efficiency boost compared to near-infrared (NIR) drivers, enabled by the favourable scaling of the single-atom response of λ-6 [1]. The experimental realization of a mulitpass cell delivering 15.7 fs pulses with a peak power close to 25 GW at 515 nm and an overall efficiency (IR to compressed green pulse) of >40 %. In conjunction, preliminary HHG results will be presented, paving the way for mW-class HHG sources at 13.5 nm.

Scan direction of circularly polarized laser beam determines the orientation of laser-induced periodic surface structures (LIPSSs) on silicon

Upon irradiation of a silicon surface with circularly polarized green nanosecond laser pulses, the formation of linear periodic nanostructures is observed. Due to the lack of inherent directional anisotropy by the laser polarization, no 1D-laser-induced periodic surface structures (LIPSSs) formation is expected. The orientation of the formed surface modulation depends on the laser scan direction. Silicon wafers, which are often used in LIPSS studies, are commonly considered inert substrates. This assumption needs to be reconsidered. Our finding is not explained by the current LIPSS theories.

EFFECTIVENESS OF CLUSTER FRONTLINE DEMONSTRATION TOWARDS TRANSFER OF SCIENTIFIC CULTIVATION PRACTICES OF MAJOR PULSES IN NAVSARI DISTRICT OF GUJARAT

The cluster frontline demonstrations (CFLDs) on pigeon pea, chick pea and summer green gram were conducted by Krishi Vigyan Kendra, Navsari. Gujarat during the year 2018-19 in three talukas of Navsari district, i.e., Chikhli, Khergam and Vansda. Total 577 demonstrations on pigeon pea, chickpea and summer green gram pulse crops were carried out in an area of 82 ha by the active participation of farmers with the objective to demonstrate the scientific cultivation practices of major pulses. The scientific cultivation practices consisting use of improved varieties, seed treatment with Thiram, rhizobium and PSB culture and management of weeds, insects and diseases. Average yield of demonstrated plots of BSMR-853, chickpea varieties of GG-3and GJG-5, and summer green gram varieties of Meha and G. mungbean-6 were recorded 10.89, 12.81, 15.32, 8.34 and 9.12 q/ha, respectively, which was 27.21, 25.96, 50.64, 42.34 and 55.63 per cent higher over check plots. Similarly, net return of 54.32, 45.29, 93.31, 97.57 and 130.35 per cent increases and B: C ratio of 2.12, 2.45, 2.93, 2.29 and 2.51 were found under pigeon pea variety of BSMR-853, chickpea varieties of GG-3 and GJG-5, and summer green gram varieties of Meha and G. M.-6, respectively.

Fused silica ablation by double ultrashort laser pulses with dual wavelength and variable delays.

Today, glass and other similar dielectric materials are widely used in modern manufacturing. However, glass is a brittle and a heat sensitive material. Laser technology is used to process glass but quality and throughput are still a key issue. In the present paper, we investigate dual-wavelength double ultrashort laser pulses in order to control free electrons dynamics and subsequent ablation for fused silica processing, and further improve the understanding of this laser-material interaction. We used a high average power Yb-doped femtosecond laser source (100 W) with two optical lines exhibiting different pulse durations and wavelengths (500 fs at 515 nm; and 1 or 10 ps at 1030 nm) with various fluences and delays. The best configuration in terms of ablation efficiency is expected to take place when the green pulse first induces free electrons, followed by their heating by the red pulse. The obtained results are discussed in terms of optical transmission as well as ablated volume, and are compared with single pulse ablation. Our experimental results are supported by absorbed energy density calculations based on a model considering the two-color laser induced electron dynamics, including photoionization, laser heating of free electrons, and their recombination. We demonstrate that there is an optimal cooperating effect between the two sub-pulses for a 1-ps delay, nevertheless there is no beneficial effect in splitting the beam for optimizing fused silica ablation compared with the single-pulse green configuration.

532-nm-modulated pulse generation based on a time-delay loop and polarization rotation.

A simple and low-cost scheme of generating 532 nm modulated pulses is investigated both theoretically and experimentally. The modulator is an external cavity based on a temporal delay loop and polarization rotation that is realized by two half-wave plates. Propagating in the temporal delay loop multiple times and being outputted partially after each round trip, the intensity of the initial green laser pulse is modulated. By analyzing the polarization of the pulse in each round trip, the pulse train is modeled to simulate the waveform of the modulated pulse. This modulator is coupled with a sub-nanosecond 532-nm-laser source to verify the model of intensity modulation. In the experiment, by rotating the HWPs, modulated pulses with various temporal profiles are obtained. The fundamental modulation frequency is calculated to be 520 MHz, and the frequency of the second harmonic also exceeds 1 GHz. Such a scheme of intensity modulation can be applied in underwater detection and ranging.

Development of green differential pulse voltammetric strategy for the determination of alfuzosin hydrochloride at pencil graphite and modified carbon paste electrodes.

A sensitive and inexpensive differential pulse voltammetric technique was applied toinvestigate the electrochemical behavior of alfuzosin hydrochloride at two different workingelectrodes: silica gel modified carbon paste and pencil graphite electrodes (PGE). Thevoltammetric conditions were optimized using cyclic voltammetry, showing an irreversibleanodic peak in Britton-Robinson buffered medium (pH 6) at 0.86-0.90 V. The electrochemicalresponses were linearly correlated with alfuzosin concentrations (R2> 0.999) in the ranges of0.6-20 and 0.3-20 μM, exhibiting higher electrocatalytic activity at PGE with a low detectionlimit/ detectability of 0.099 μM. In addition, this study was a successful attempt for the drugdetermination in tablets and spiked urine samples with green profile evaluation, employing theNational Environmental Methods Index, analytical Eco-Scale score, and Green AnalyticalProcedure Index.

Ta2O5-graphene Schottky heterojunction composite symmetric supercapacitor with ultrahigh energy density for self-powered pulse sensor driven by green long afterglow phosphor-enhanced solar cell

Ta2O5 has received great attention in high-energy supercapacitors because of biocompatibility, multielectron redox and wide voltage window, but poor electronic conductivity limits its practical applications. The study reports synthesis of Ta2O5-graphene composite (G-Ta2O5) mediated by salicylic acid ionic liquid. The synthesis strategy realizes three-dimensional structure, excellent dispersion, small size of G-Ta2O5 nanorods and Schottky heterojunction. The unique structure improves the electronic conductivity and expands voltage window to 2 V. The G-Ta2O5 symmetrical supercapacitors exhibits ultrahigh specific capacitance of 554.7F g−1 at 1 A g−1, rate-capacity of 227.7F g−1 at 50 A g−1, capacity retention of 99.6% after 10,000 cycles at 1 A g−1 and energy density of 77.04 W h Kg−1 at 503.52 W kg−1. The supercapacitors was integrated with green long afterglow phosphor-enhanced solar cell and pulse device to construct wearable self-powered pulse sensor system. The introduction of phosphor brings an increases of 5.14% in the photocurrent during day time and an additional electric energy required for the sensor to work for more than 3 h at night. The sensor system can work for a long time no need of any additional power supply and shows one broad application prospect in disease diagnosis and monitoring health.

Gain-switching in CsPbBr3 microwire lasers

All-inorganic perovskite microwire lasers, which have intrinsic high material gain and short cavity, especially favor the generation of ultrashort optical pulses via gain switching for various potential applications. Particularly, the ultrashort gain-switched pulses may extend perovskite microwires to previously inaccessible areas, such as ultrafast switches, and chipscale microcombs pumping souces in photonic integrated circuits. Here, we show 13.6-ps ultrashort single-mode green pulses from the gain-switched CsPbBr3 microwire lasers under femtosecond optical pumping. The gain-switching dynamics is experimentally investigated by a streak camera system. The excitation fluence dependences of pulse width, delay time and rise time of the output pulses show good agreements with the rate equation simulations with taking gain nonlinearities and carrier recombination ABC model into account. Our results reveal that perovskite microwire lasers have potential for ultrashort pulse generation, while the low transient saturated gain, which may result from the high transient carrier temperature under femtosecond pumping is a significant limitation for further pulse shortening.

Determination of atomic multiphoton-ionization phases by trichromatic multichannel wave-packet interferometry

We present the unambiguous determination of quantum phases in the multiphoton ionization (MPI) of potassium atoms by using a multichannel photoelectron interferometry scheme based on trichromatic pulse shaping. The colors of the laser field are chosen to produce three energetically separated photoelectron interferograms in the continuum. While the red pulse is two-photon resonant with the $3d$ state resulting in a $(2+1)$ resonance-enhanced MPI (REMPI), a $(1+2)$ REMPI occurs via the nonresonant intermediate $4p$ state with an initial green or blue pulse. We show that ionization via a nonresonant intermediate state lifts the degeneracy of photoelectron interferograms from pathways consisting of permutations of the colors. The analysis of the interferograms reveals a phase shift of $\ifmmode\pm\else\textpm\fi{}\ensuremath{\pi}/2$ depending on the sign of the detunings in the $(1+2)$ REMPI pathways. In addition, we demonstrate that the photoionization time delay in the resonant $(2+1)$ REMPI pathway gives rise to a linear spectral phase in the photoelectron spectra. Insights into the underlying MPI processes are gained through an analytic perturbative description and numerical simulations of a trichromatic driven three-level system coupled to the continuum.

Passively Q-switched microchip laser based picosecond light source in the visible-red to near-infrared band for semiconductor excitation.

We developed a visible-red to near-infrared wavelength tunable all-solid-state laser system utilizing an optical parametric generation process in a MgO doped PPLN crystal pumped at 532 nm by an amplified and frequency doubled picosecond passively Q-switched Nd:YVO4 microchip laser. A broad bandwidth, tuneable over 300 nm between 710 nm to 1015 nm, is accessible. Depending on the green pump light pulse energy, pulses with durations down to 69 ps as well as pulses with energies above 2 µJ were achieved with kHz repetition rates.

Endocrine Disruptors-'Food' for Thought.

Green vegetables, fruits, cereals, and pulses are all rich sources of antioxidants. Retinoic acid, ascorbate, proanthocyanidins, tannins, saponins, melatonin, curcumin, allicin, and alpha-lipoic acid stand documented in plants as bioactive compounds. The international dietary committee advocates a specific quantum of these natural antioxidants through diet. Interestingly, environmental pollution has indeed affected most of these farm products. The use of chemical fertilizers, pesticides and heavy metals in soil has a cumulative effect on human health. Enough evidence is available for the presence of phytoestrogen, xenoestrogen, and a host of other endocrine disruptors in the food. These plant-based nutrients can mimic or enhance the natural hormone's health effects. While endocrine disruptors are found in many everyday products, this review aims to address endocrine disruptors from food in the Asian subcontinent. 'Food for thought' justifies the paradigm shift towards good endocrine health by swaying away from the conventional daily dietary recommendations.

Absorption of Pulsed Terahertz and Optical Radiation in Earthworm Tissue and Its Heating Effect

The transmission of THz, near-infrared (1030 nm), and green (515 nm) pulses through Eisenia andrei body wall is studied, which consists of epithelial layer and circular and longitudinal muscles. Samples with the full-body cross-section were also investigated. The transmitted power for the green pulses followed the Beer-Lambert law of exponential attenuation for all thicknesses and tissue structures. Different body wall and body center absorption coefficients were found in case of infrared pulses. In the THz range, the body wall absorption coefficient steadily increases from about 80 cm–1 at 0.2 THz to about 273 cm–1 at 2.5 THz. Numerical estimation indicates that THz pulses of 5-μJ energy and 1-kHz repetition rate (5-mW average power) cause only a small temperature increase of about 0.4 K, suggesting that heating has minor contribution to biological effectiveness.