Total Laser Energy Research Articles

Endovenous laser ablation treatment with 980 nm diode laser for saphenous vein insufficiency: 6 months follow up results.

Superficial venous insufficiency is a common problem associated with varicose veins which, if untreated, may progress to venous ulceration. Endovenous laser ablation (EVLA) is a new, minimally invasive method for management of superficial venous insufficiency and varicose veins. The aim of this study was to demonstrate the effectiveness of 980 nm EVLA for treatment of symptomatic saphenous venous insufficiency and to present its early outcomes. Thirty-eight great saphenous veins and 5 small saphenous veins in 40 patients with saphenofemoral reflux were treated with 980 nm diode endovenous laser equipment. The diameter and length of the vein treated, total laser energy and energy density (Joules/cm) delivered were recorded. To determine the severity of the venous disease Venous Clinical Severity Score (VCSS) and Visual Analogue Scale (VAS) were used. Patients were followed up for 6 months after the procedure. Complications were recorded prospectively. Forty-three saphenous veins in 40 patients were treated. The mean age of the patients was 39.9 (range 21-72) years. The mean diameter and length of the veins were 4.9 mm (range, 3.5 to 8.5 mm) and 30.2 cm (range, 16 to 50 cm), respectively. At 6 months follow-up, total occlusion rate was 95.4% (41/43), and recanalization rate was 4.6%. Significant decrease was observed for VCSS and VAS scores after the procedure. No major complication was detected. EVLA treatment for superficial venous insufficiency is safe and can be carried out under local anaesthesia in an outpatient setting with good patient satisfaction and low complication rates.

Effects of holmium laser enucleation of the prostate on sexual function.

To evaluate the effects of holmium laser enucleation of the prostate (HoLEP) on sexual function. A retrospective analysis of 202 sexually active patients who underwent HoLEP was performed. Patients were assessed at baseline and 3 and 12 months post-HoLEP. Evaluations included uroflowmetry and symptom questionnaires (five-item version of the International Index of Erectile Function [IIEF-5], ICIQ-male sexual matters associated with LUTS [ICIQ-MLUTSsex], American Urological Association symptom score [AUA-SS], and single-question quality of life [QoL] score). Nonparametric, Fisher's exact, and chi-squared tests were used to assess changes from baseline and to identify risk factors, if any, associated with deterioration of sexual function after surgery. No significant differences were found between the preoperative and postoperative scores on the questionnaires that evaluated erection quality. However, 6.9% and 12.4% of the patients reported an increase or a reduction, respectively, of greater than five points in total IIEF-5 score. The reduction in IIEF-5 score was statistically significant only in the subgroup of patients without preoperative erectile dysfunction (ED). No preoperative characteristics and no parameters related to the surgery or postoperative outcome were significantly associated with the impairment of erection quality after surgery. In fact, neither capsular perforation nor the total laser energy used during the procedure affected erections. Loss of antegrade ejaculation was found in 70.3% of patients, while 21% reported a reduction in semen quantity. However, concern regarding ED or ejaculatory dysfunctions decreased with surgery. Although erectile function was not altered in the vast majority of patients after HoLEP, patients without preoperative ED displayed a relatively small, but still significant, negative effect on erections. The overwhelming majority of patients suffered from retrograde ejaculation after surgery.

Repetitive Pulse Performance of One-Micrometer Laser-Ablation Propulsion onto Aluminum

The impulse characteristics of an aluminum ablator against repetitive Nd:YLF laser pulses with a 1047 nm wavelength and 5 to 15 ns pulsewidth were investigated. The laser was operated in burst mode varying the pulse repetition frequency, single-pulse energy, and number of pulses in a burst. The burst was repeated until the impulse reached saturation. A torsion pendulum was used to measure the total impulse generated in a single burst with an accuracy higher than 2%, even with a 1 s burst period. The impulse increased, and then it gradually reached saturation as the total laser energy increased. In the operation range examined, the saturation value of the impulse increased with increasing single-pulse fluence.

Analysis of Potassium Titanyl Phosphate Laser Settings and Voice Outcomes in the Treatment of Reinke’s Edema

Despite increased clinical utility of the 532-nm potassium titanyl phosphate (KTP) laser, no studies have examined outcomes for Reinke's edema (RE) as a function of laser parameters and initial treatment effects. Variability in delivery parameters, fiber-to-tissue distance, and immediate end-tissue effects limits universal application of existing study outcomes. We examine voice outcomes using standardized treatment classification, providing justification for laser parameter selection and immediate tissue effect in clinical use. Retrospective review of 9 patients who underwent KTP laser treatment for RE. Demographics, RE severity, laser settings, total laser energy, and immediate tissue effects were correlated with quantified voice outcomes. An average of 157 joules (6-640 J) was delivered over a 0.369-second exposure time (0.1-0.9 seconds). Immediate tissue effects varied from nonablative treatment (type I and type II) to ablation without tissue removal (type III). Overall, Voice Handicap Index-10 (VHI-10) decreased by 8.23; improvement was most pronounced with type II treatments (delta VHI-10=12). No complications were encountered. Potassium titanyl phosphate laser can be safely and effectively used to improve voice in RE patients regardless of severity. This is the first study to provide detailed information on laser settings, energy delivery, and treatment effect in RE management; these results may guide clinical use of this modality, especially for novice laser surgeons.

Colliding laser-produced plasmas as targets for laser-generated extreme ultraviolet sources

Colliding plasmas produced by neodymium-doped yttrium aluminium garnet (Nd:YAG) laser illumination of tin wedge targets form stagnation layers, the physical parameters of which can be controlled to optimise coupling with a carbon dioxide (CO2) heating laser pulse and subsequent extreme ultraviolet (EUV) production. The conversion efficiency (CE) of total laser energy into EUV emission at 13.5 nm ± 1% was 3.6%. Neglecting both the energy required to form the stagnation layer and the EUV light produced before the CO2 laser pulse is incident results in a CE of 5.1% of the CO2 laser energy into EUV light.

Fabrication of Finely Pitched LYSO Arrays Using Subsurface Laser Engraving Technique with Picosecond and Nanosecond Pulse Lasers

We propose to adopt the subsurface laser engraving (SSLE) technique for efficient and precise fabrication of finely pitched scintillation crystal arrays. However, its application to thicker crystals is still challenging. It is difficult to focus the laser beam tightly at a point far from the crystal's surface because of the large refractive index of the scintillator. Therefore, a higher laser energy is needed to create microcracks at deep positions in the crystal. Because this would cause excessive damage to the scintillation crystal during laser scans, the process yield of SSLE is reduced. We found that this issue could be overcome by a novel SSLE technique using both picosecond (ps) and nanosecond (ns) pulse lasers. The experimental results indicated that the total laser energy required for creating microcrack walls in a LYSO crystal can be reduced compared to that of conventional SSLE using only a ns pulse laser. The SSLE technique using both ps and ns pulse lasers would enable the fabrication of finely pitched LYSO arrays with a higher process yield.

Energetics measurements of silver halfraum targets at the National Ignition Facility

The energetics of novel silver halfraum targets are presented from laser experiments at the National Ignition Facility (NIF). Four beams from the NIF laser were used to heat the halfraum targets with ∼10 kJ of energy in a 1 ns square laser pulse. The silver halfraum targets were spheres 2 mm in diameter with an 800 μm laser entrance hole (LEH). Targets with different spherical wall thicknesses (8–16 μm) were characterized. The energetics and the laser coupling to the targets were determined using the NIF X-ray (i.e. Dante and FFLEX spectrometers) and optical backscatter diagnostics (NBI and FABS). The energy coupled into the targets was 0.85–0.88 of the total laser energy with a defocused laser spot of 400 μm in diameter and no spatial smoothing of the beams with phase plates. The coupling increased to 0.92 when 400 μm spot size phase plates were used to smooth each of the four lasers beams. The energy losses from the targets were through X-ray radiation and backscatter from laser plasma instabilities (SBS and SRS) from the LEH. As expected the different wall thickness had different levels of burn through emission. The thickest walled target (∼15.9 μm) had very low radiative losses through the target wall. The thinnest walled targets (∼8 μm) radiated about 0.2 of the input energy into X-ray emission.

Efficient Intracellular Delivery of Molecules with High Cell Viability Using Nanosecond-Pulsed Laser-Activated Carbon Nanoparticles

Conventional physical and chemical methods that efficiently deliver molecules into cells are often associated with low cell viability. In this study, we evaluated the cellular effects of carbon nanoparticles believed to emit photoacoustic waves due to nanosecond-pulse laser activation to test the hypothesis that this method could achieve efficient intracellular delivery while maintaining high cell viability. Suspensions of DU145 human prostate carcinoma cells, carbon black (CB) nanoparticles, and calcein were exposed to 5–9 ns long laser pulses of near-infrared (1064 nm wavelength) light and then analyzed by flow cytometry for intracellular uptake of calcein and cell viability by propidium iodide staining. We found that intracellular uptake increased and in some cases saturated at high levels with only small losses in cell viability as a result of increasing laser fluence, laser exposure time, and as a unifying parameter, the total laser energy. Changing interpulse spacing between 0.1 and 10 s intervals showed no significant change in bioeffects, suggesting that the effects of each pulse were independent when spaced by at least 0.1 s intervals. Pretreatment of CB nanoparticles to intense laser exposure followed by mixing with cells also had no significant effect on uptake or viability. Similar uptake and viability were seen when CB nanoparticles were substituted with India ink, when DU145 cells were substituted with H9c2 rat cardiomyoblast cells, and when calcein was substituted with FITC-dextran. The best laser exposure conditions tested led to 88% of cells with intracellular uptake and close to 100% viability, indicating that nanosecond-pulse laser-activated carbon nanoparticles can achieve efficient intracellular delivery while maintaining high cell viability.

Determinants of Holmium:Yttrium–aluminum-garnet Laser Time and Energy During Ureteroscopic Laser Lithotripsy

To evaluate the association of preoperative noncontrast computed tomography stone characteristics, laser settings, and stone composition with cumulative holmium:yttrium-aluminum-garnet (Ho:YAG) laser time/energy. We retrospectively reviewed patients who underwent semirigid/flexible ureteroscopy and Ho:YAG laser lithotripsy (200 or 365 μm laser fiber; 0.8-1.0 J energy; and 8-10 Hz rate) at 2 tertiary care centers (April 2010-May 2012). Studied parameters were as follows: patient's characteristics; stone characteristics (location, burden, hardness, and composition); total laser time and energy; and surgical outcomes. One hundred patients met our inclusion criteria. Mean stone size was 1.01 ± 0.42 cm and volume 0.33 ± 0.04 cm(3). Mean stone radiodensity was 990 ± 296 HU, and Hounsfield units density 13.8 ± 6.0 HU/mm. All patients were considered stone free. Stone size and volume had a significant positive correlation with laser energy (R = 0.516, P <.001; R = 0.621, P <.001) and laser time (R = 0.477, P <.001; R = 0.567, P <.001). When controlling for stone size, only the correlation between HU and laser time was significant (R = 0.262, P = .011). In the multivariate analysis, with exception of stone composition (P = .103), all parameters significantly increased laser energy (R(2) = 0.524). Multivariate analysis revealed a positive significant association of laser time with stone volume (P <.001) and Hounsfield units density (P <.001; R(2) = 0.512). In multivariate analysis for laser energy, only calcium phosphate stones required less energy to fragment compared with uric acid stones. No significant differences were found in the multivariate laser time model. Ho:YAG laser cumulative energy and total time are significantly affected by stone dimensions, hardness location, fiber size, and power. Kidney location, laser fiber size, and laser power have more influence on the final laser energy than on the total laser time. Calcium phosphate stones require less laser energy to fragment.

Proficiency of virtual reality simulator training in flexible retrograde ureteroscopy renal stone management

Background Minimally invasive flexible ureteroscopy techniques have widely adopted in the management of patients with renal stones. We performed this study to investigate the value of virtual reality simulator training in retrograde flexible ureteroscopy renal stone treatment for catechumen. Methods Thirty catechumen, included 17 attending physicians and 13 associate chief physicians, were selected for study. The trainees first underwent 1-hour basic training to get familiar with the instrument and basic procedures, then followed by 4-hour practice on virtual reality simulators. Before and after the 4-hour training, all trainees undertake an assessment with task 7 program (right low pole calyces stone management). We documented for each trainee the total time of procedure, time of progressing from the orifice to stone, stone translocation and fragmentation time, laser operate proficiency scale, total laser energy, maximal size of residual stone fragments, number of trauma from the scopes and tools, damage to the scope and global rating scale (GRS). The proficiency of this training program was analyzed by the comparison of the first and second assessment outcomes. Results Significant improvement was observed in retrograde flexible ureteroscopy management of renal stone on virtual reality simulators after finishing the 4 hour special-purpose training. This was demonstrated by improvement in total procedure time ((18.37±2.59) minutes vs. (38.67±1.94) minutes), progressing time from the orifice to stone ((4.00±1.08) minutes vs. (13.80±2.01) minutes), time of stone translocation ((1.80±0.71) minutes vs. (6.57±1.01) minutes), fragmentation time ((4.43±1.25) minutes vs. (13.53±1.46) minutes), laser operate proficiency scale (8.47±0.73 vs. 3.77±0.77), total laser energy ((3231.6±401.4) W vs. (5329.8±448.9) W), maximal size of residual stone fragments ((2.66±0.39) mm vs. (5.77±0.63) mm), number of trauma from the scopes and tools (3.27±1.01 vs. 10.37±3.02), damage to the scope (0 vs. 0.97±0.76) and GRS (29.27±2.95 vs. 9.87±2.21). The differences between the first and the second assessment were all statistically significant (all P &lt;0.01). Conclusion The virtual reality simulator training program can help the trainees to rapidly improve their retrograde flexible ureteroscopy skill in renal stone treatment.

Corneal changes after a single session of selective laser trabeculoplasty for open-angle glaucoma

To investigate the changes in endothelial cell count, central corneal thickness (CCT), and refractive error after a session of selective laser trabeculoplasty (SLT) for open angle glaucoma (OAG). This prospective cohort study recruited 111 eyes of 66 consecutive subjects with OAG. Subjects received SLT to 360° of the trabecular meshwork. Endothelial cell count, CCT, and spherical equivalent were measured at baseline before SLT as well as at 1 week and 1 month post SLT. A repeated measure nested ANOVA with Tukey's multiple comparison test was performed to compare the outcome measures before and after SLT. In 111 eyes of 66 subjects, the mean number of laser applications per treatment was 166.9 ± 41.4 with a mean energy level of 1.0 ± 0.07 mJ. The mean endothelial cell count decreased significantly from 2465.0 ± 334.0 cells/mm(2) at baseline to 2355.0 ± 387.0 cells/mm(2) at 1 week (P=0.0004) but increased to baseline levels at 1 month post SLT (2424.0 ± 379.4 cells/mm(2), P=0.3). The CCT, which decreased from a baseline of 549.4 ± 37.6 to 543.9 ± 40.2 μm at 1 week post SLT (P=0.02), also returned to the baseline level by 1 month (P=0.2). The spherical equivalent was static from baseline. A positive correlation was found between total laser energy and CCT at 1 month post treatment (r=0.3, P=0.005). The transient reductions in endothelial cell count and CCT following SLT returned to baseline levels 1 month after the procedure. Patients undergoing SLT should be aware of the risk of potential corneal changes.

Computational Simulation of Temperature Elevations in Tumors Using Monte Carlo Method and Comparison to Experimental Measurements in Laser Photothermal Therapy

Accurate simulation of temperature distribution in tumors induced by gold nanorods during laser photothermal therapy relies on precise measurements of thermal, optical, and physiological properties of the tumor with or without nanorods present. In this study, a computational Monte Carlo simulation algorithm is developed to simulate photon propagation in a spherical tumor to calculate laser energy absorption in the tumor and examine the effects of the absorption (μ(a)) and scattering (μ(s)) coefficients of tumors on the generated heating pattern in the tumor. The laser-generated energy deposition distribution is then incorporated into a 3D finite-element model of prostatic tumors embedded in a mouse body to simulate temperature elevations during laser photothermal therapy using gold nanorods. The simulated temperature elevations are compared with measured temperatures in PC3 prostatic tumors in our previous in vivo experimental studies to extract the optical properties of PC3 tumors containing different concentrations of gold nanorods. It has been shown that the total laser energy deposited in the tumor is dominated by μ(a), while both μ(a) and μ(s) shift the distribution of the energy deposition in the tumor. Three sets of μ(a) and μ(s) are extracted, representing the corresponding optical properties of PC3 tumors containing different concentrations of nanorods to laser irradiance at 808 nm wavelength. With the injection of 0.1 cc of a 250 optical density (OD) nanorod solution, the total laser energy absorption rate is increased by 30% from the case of injecting 0.1 cc of a 50 OD nanorod solution, and by 125% from the control case without nanorod injection. Based on the simulated temperature elevations in the tumor, it is likely that after heating for 15 min, permanent thermal damage occurs in the tumor injected with the 250 OD nanorod solution, while thermal damage to the control tumor and the one injected with the 50 OD nanorod solution may be incomplete.

Does previous failed ESWL have a negative impact of on the outcome of ureterorenoscopy? A matched pair analysis

This study aims to evaluate the outcome of ureteroscopy/ureterorenoscopy (URS) as a salvage procedure for stones resistant to extracorporeal shock wave lithotripsy (ESWL). Between January 2009 and January 2012, 313 patients with upper tract lithiasis were treated by URS. Among them, 87 (27.8%) had undergone URS after prior ESWL failed to achieve stone clearance (Salvage group). These patients were matched with a group of patients who underwent URS as first-line modality (Primary group). Stone-free rates and adjuvant procedures represented the primary points for comparison. Secondary points for comparison included complications, procedure duration, total laser energy used and length of hospitalization. Matching was possible in all cases. Stone clearance rates were 73.6 and 82.8% for the Salvage and Primary group, respectively. The difference in stone clearance rates between the two groups was not statistically significant (p=0.186). A total of 11 patients (12.6%) in the Primary group and 18 patients (20.7%) in the Salvage group underwent an adjuvant procedure (p=0.154). No statistically significant differences were noted in terms of complications, procedure duration and length of hospitalization. In the Primary group, the laser energy used for stone fragmentation was higher (p=0.043). The rate of ureteric stenting at the end of the procedure was higher for the Salvage group (p=0.030). Previous failed ESWL is not a predictor for unfavorable outcome of URS. Salvage URS is associated, however, with an increased need for ureteric stenting at the end of the procedure.

Selective Laser Trabeculoplasty Following Failed Combined Phacoemulsification Cataract Extraction and Ab Interno Trabeculectomy

To assess the effect of selective laser trabeculoplasty (SLT) following failed phacoemulsification cataract extraction combined with ab interno trabeculectomy (AIT) using the Trabectome (phaco-trabectome). Randomized, interventional case series. Retrospectively, the medical records of patients who underwent SLT between March 2010 and July 2012 by 1 surgeon at a single center after a failed phaco-AIT were evaluated. Inclusion criteria were age ≥18 years with no upper limit and prior failed phaco-AIT attributable to glaucoma progression. Exclusion criterion was performance of any additional glaucoma procedure with influence on intraocular pressure (IOP) during follow-up and a follow-up after surgery of <3 months. Success was defined by reduction of IOP of >3 mm Hg and 20% and number of antiglaucoma medications equal to or less than baseline. Main outcome measures were IOP, antiglaucoma medications, time to failure, and Kaplan-Meier survival curve. Fourteen eyes of 13 subjects were included. Mean follow-up after SLT was 12.9 ± 8.7 months. Total laser energy was 59.5 ± 8.7 mJ. Baseline IOP was 17.9 ± 3.3 mm Hg and number of antiglaucoma medications at baseline was 2.0 ± 1.0. All SLT procedures failed. Median time to failure after SLT was 3.6 ± 0.8 (range 2.1-5.1) months. Number of antiglaucoma medications did not change. In eyes in which the IOP was no longer controlled following phaco-trabectome, SLT had a limited duration of significant IOP-lowering effect. Other alternatives, such as incisional filtration surgery, should be considered following failed phaco-trabectome.

Developments in Direct Drive Laser Fusion

Recent designs for laser driven, direct drive inertial confinement fusion (ICF) indicate that substantial gains (G>100) might be achieved with lower total laser energy (E~500 kJ) than previously considered possible. A leading contender is the shock ignition approach which compresses low aspect ratio pellets with high intensity laser pulses (1015 W/cm2) before achieving ignition with a final higher intensity spike (1016 W/cm2). Excimer laser systems based on a krypton-fluoride (KrF) medium are particularly well suited to these new ideas as they operate in the ultraviolet (248 nm), provide highly uniform illumination, possess large bandwidth (1-3 THz), and can easily exploit beam zooming to improve laser-target coupling for the final spike pulse. This paper will examine target physics advantages of KrF lasers in relation to the new implosion designs and the balancing of hydrodynamic instability and laser-plasma instabilities. Supporting experimental and theoretical studies of are being conducted by the Nike laser group at the U. S. Naval Research Laboratory. Recent experimental work has also shown that the high ablation pressures and smooth profiles obtained with the Nike laser can be used to accelerate planar targets to velocities consistent with the requirements of impact ignition.

Anterior Chamber Bleeding After Laser Peripheral Iridotomy

To our knowledge, this is the first study to describe the correlation of anterior chamber bleeding after laser peripheral iridotomy (LPI) and antiplatelet therapy. To determine the incidence and amount of anterior chamber bleeding after laser peripheral iridotomy in patients whose condition is suggestive of primary angle-closure glaucoma (PACS) who continued their antiplatelet or anticoagulant treatment before undergoing LPI compared with when they discontinued treatment. A prospective controlled trial. Patients with suspected bilateral primary angle-closure and no other ocular disease who take antiplatelet or anticoagulant medications regularly (from January 2010-October 2011) were enrolled. The incidence of anterior chamber bleeding with and without antiplatelet and anticoagulant therapy. A total of 104 patients (208 eyes) participated in the study. Thirty-six eyes (34.6%) in the treated and untreated arms bled. The amount of bleeding did not differ significantly when the patient was on or off antiplatelet or anticoagulant treatment, nor did the immediate postprocedure mean intraocular pressure (P = .13). The type of antiplatelet or anticoagulant, total laser energy, age, sex, or color of irides were not risk factors for increased bleeding (P = .156 for all parameters). No indication was noted for discontinuing these medications before a high-powered pulsed laser peripheral iridotomy.

Incidence of hypotony and sympathetic ophthalmia following trans‐scleral cyclophotocoagulation for glaucoma and a report of risk factors

To report the incidence and risk factors for hypotony and estimate the risk of sympathetic ophthalmia following diode laser trans-scleral cyclophotocoagulation (TSCPC). Retrospective study using data from a private tertiary glaucoma clinic and review of the literature. Seventy eyes of 70 patients with refractory glaucoma who received TSCPC treatment. Review of the records of consecutive patients who underwent TSCPC by a single ophthalmic surgeon and review of the literature. Hypotony (including phthisis bulbi), sympathetic ophthalmia. Seven eyes (10%; CI 5-19%) developed hypotony and included 4 eyes that developed phthisis. Higher total energy delivered during TSCPC treatment was associated with an increased risk of hypotony: eyes that developed hypotony received a mean total energy of 192.5 ± 73.2 joules, compared to a mean of 152.9 ± 83.2 joules in hypotony-free cases. The risk of sympathetic ophthalmia estimated from a review of the published literature and current series was one in 1512, or 0.07% (CI 0.03%-0.17%). Total laser energy is one of several risk factors that act in a sufficient component cause-model to produce hypotony in an individual patient. The small sample size precluded inference for other individual putative risk factors but titrating laser energy may help decrease the occurrence of hypotony. The risk of sympathetic ophthalmia calculated from the literature is likely an overestimate caused by publication bias.

Pulp Responses After CO2Laser Irradiation of Rat Dentin

The purpose of this study was to investigate pulp responses after CO(2) laser irradiation of rat molars using reverse transcription polymerase chain reaction (RT-PCR) and immunohistochemical methods. Many kinds of lasers have been used for the treatment of dentin hypersensitivity. However, the immunohistochemical details of the responses of dentin-pulp complex cells after CO(2) laser irradiation through the dentin are still not clear. Adult male Sprague-Dawley rats were used in this study. A CO(2) laser (wavelength of 10.6 μm, 2 W in the super pulse mode, pulse 0.6 ms) and total laser energy of 4 J (density, 203.84 J/cm(2)) was used. The temperature change in the pulp was measured using a super fine sheath thermocouple. The temperature at the pulp side after the CO(2) laser irradiation increased 22.5°C. The expression of tumor necrosis factor-alpha (TNF-α) and interleukin (IL)-1-α mRNAs was significantly higher at 6, 12, and 24 h after laser irradiation than in the control group (p<0.05). Histologically, a slight degeneration of the pulp tissue was observed immediately after the laser irradiation. Immunohistochemically, heat shock protein (HSP)-70-positive cells in the pulp horn were observed immediately after irradiation and cells positive for vascular endothelial growth factor (VEGF) in the subodontoblast layer were observed after 5 days. There were no nestin-positive cells immediately, but after 5 days nestin-positive cells were recognized in the deeper pulp cells. Immediately after irradiation, neurofilament protein (NFP)-positive nerve fibers were observed but they disappeared in the pulp horn after 5 days. These results suggest that 203.84 J/cm(2) CO(2) laser irradiation of pulp tissue through the dentin, such as is used in the clinic, induces inflammatory and pathological cytokine pathways to repair the damaged pulp tissue.

Studies on shock ignition targets for inertial fusion energy

Shock-ignited inertial fusion targets are studied by one dimensional and two-dimensional numerical simulations. Most of the study refers to the simple all-DT HiPER baseline target (imploded mass of 0.29 mg); both the reference laser wavelength λ = 0.35 μm, and λ = 0.25 μm are considered. The target achieves 1D gain about 80 (120) with total laser energy of 260 kJ (180 kJ) at λ = 0.35 μm (0.25 μm). Operating windows for the parameters of the laser ignition spike are described. According to preliminary simulations, gain 80–100 is also obtained by a scaled target (imploded mass of 1.8 mg) driven by 1.5 MJ of green laser light (0.53 μm). Two dimensional simulations indicate robustness to irradiation nonuniformities, and high sensitivity to target mispositioning. This can however be reduced by increasing the power of the ignition spike.

Total energy loss to fast ablator-ions and target capacitance of direct-drive implosions on OMEGA

Measurements of the total energy carried by fast ablator-ions in direct-drive implosions on OMEGA have been conducted using magnetic and Thomson Parabola spectrometers. It is shown that the total laser energy lost to fast ablator-ions for plastic and glass targets is comparable and that it is a modest fraction of the incident laser energy (≲1%). These measurements have been used to infer a non-linear, voltage-dependent target capacitance (∼0.1 nF) associated with the space-charge that accelerates the fast-ions.