Self-Trapping of Slow Electrons in the Energy Domain.

The interaction of light and swift electrons has enabled phase-coherent manipulation and acceleration of electron wave packets. Here, we investigate this interaction in a new regime where low-energy electrons (∼20-200 eV) interact with a phase-matched light field. Our analytical and one-dimensional numerical study shows that slow electrons are subject to strong confinement in the energy domain due to the nonvanishing curvature of the electron dispersion. The spectral trap is tunable and an appropriate choice of light field parameters can reduce the interaction dynamics to only two energy states. The capacity to trap electrons expands the scope of electron beam physics, free-electron quantum optics and quantum simulators.

Protective Effect of Amblyopia on Age-Related Macular Degeneration.

PURPOSE: Our aim was to evaluate whether patients with age-related macular degeneration (AMD) and cooccurrent amblyopia are more likely to have diseases diagnosed on both the ipsilateral and the contralateral side in a large Austrian database. DESIGN: Retrospective cross-sectional study. METHODS: Setting: Institutional practice. PATIENT POPULATION: Medical records of all patients who visited the Department of Ophthalmology of the Medical University of Graz between December 1996 and June 2021 were searched for the co-occurrence of AMD and amblyopia. MAIN OUTCOME MEASURES: Data from patients with AMD diagnosed on 1 eye side were used for further analysis. Spectral-domain optical coherence tomography images were analyzed to confirm the lateral asymmetry of AMD. RESULTS: A total of 327,443 patients were screened for the co-occurrence of AMD and amblyopia. Of them, 8742 patients had AMD diagnosed on 1 eye side and 5051 patients had unilateral amblyopia. In total, 163 patients were found to have AMD diagnosed on 1 side and unilateral amblyopia in combination. Of these, 126 patients had AMD and amblyopia on contralateral sides and 37 had AMD and amblyopia on the ipsilateral side (P < .001). CONCLUSIONS: Less amblyopic patients had AMD diagnosed on the amblyopic eye compared with the nonamblyopic eye. In cases of lateral asymmetry, the nonamblyopic eye is more likely to have the more advanced form of AMD.

Lossless Monochromator in an Ultrafast Electron Microscope Using Near-Field THz Radiation.

The ability to form monoenergetic electron beams is vital for high-resolution electron spectroscopy and imaging. Such capabilities are commonly achieved using an electron monochromator, which energy filters a dispersed electron beam, thus reducing the electron flux to yield down to meV energy resolution. This reduction in flux hinders the use of monochromators in many applications, such as ultrafast transmission electron microscopes (UTEMs). Here, we develop and demonstrate a mechanism for electron energy monochromation that does not reduce the flux-a lossless monochromator. The mechanism is based on the interaction of free-electron pulses with single-cycle THz near fields, created by nonlinear conversion of an optical laser pulse near the electron beam path inside a UTEM. Our experiment reduces the electron energy spread by a factor of up to 2.9 without compromising the beam flux. Moreover, as the electron-THz interaction takes place over an extended region of many tens of microns in free space, the realized technique is highly robust-granting uniform monochromation over a wide area, larger than the electron beam diameter. We further demonstrate the wide tunability of our method by monochromating the electron beam at multiple primary electron energies from 60 to 200 keV, studying the effect of various electron and THz parameters on its performance. Our findings have direct applications in the fast-growing field of ultrafast electron microscopy, allowing time- and energy-resolved studies of exciton physics, phononic vibrational resonances, charge transport effects, and optical excitations in the mid IR to the far IR.

Quantum wave function reconstruction by free-electron spectral shearing interferometry.

The quantum wave function measurement of a free electron remains challenging in quantum mechanics and is subject to disputes about ψ-ontic/epistemic interpretations of the wave function. Here, we theoretically propose a realistic spectral method for reconstructing quantum wave function of an electron pulse, free-electron spectral shearing interferometry (FESSI). We use a Wien filter to generate two time-delayed replicas of the electron wave packet and then shift one replica in energy using a light-electron modulator driven by a mid-infrared laser. As a direct demonstration, we numerically reconstruct a pulsed electron wave function with a kinetic energy of 10 keV. FESSI is experimentally feasible and enables us to fully determine distinct orders of spectral phases and their physical implications in quantum foundations and quantum technologies, providing a universal approach to characterize ultrashort electron pulses.

Self-Made Sleeve for Chandelier Light Simulation.

PURPOSE: To develop a quick and cost-effective alternative to a chandelier light for vitrectomy. METHODS: The surgical material available in an ophthalmologic operating room was used to create a sleeve for the vitrectomy light probe and tested on 30 consecutive retinal detachment cases for feasibility. RESULTS: A 64 × 5-mm cotton swab stick was cut into the length of the light probe minus the length of the trocar and subsequently pierced by a blunt needle. With this sleeve, the light probe could be safely handled similar to a chandelier light during surgery. CONCLUSION: A sleeve for the light probe can serve as a substitute for a chandelier light during scleral depression in retinal detachment surgery.

Infectious Complications after Etomidate vs. Propofol for Induction of General Anesthesia in Cardiac Surgery-Results of a Retrospective, before-after Study.

BACKGROUND: Etomidate is typically used as an induction agent in cardiac surgery because it has little impact on hemodynamics. It is a known suppressor of adrenocortical function and may increase the risk for post-operative infections, sepsis, and mortality. The aim of this study was to evaluate whether etomidate increases the risk of postoperative sepsis (primary outcome) and infections (secondary outcome) compared to propofol. METHODS: This was a retrospective before-after trial (IRB EA1/143/20) performed at a tertiary medical center in Berlin, Germany, between 10/2012 and 01/2015. Patients undergoing cardiac surgery were investigated within two observation intervals, during which etomidate and propofol were the sole induction agents. RESULTS: One-thousand, four-hundred, and sixty-two patients, and 622 matched pairs, after caliper propensity-score matching, were included in the final analysis. Sepsis rates did not differ in the matched cohort (etomidate: 11.5% vs. propofol: 8.2%, p = 0.052). Patients in the etomidate interval were more likely to develop hospital-acquired pneumonia (etomidate: 18.6% vs. propofol: 14.0%, p = 0.031). CONCLUSION: Our study showed that a single-dose of etomidate is not statistically associated with higher postoperative sepsis rates after cardiac surgery, but is associated with a higher incidence of hospital-acquired pneumonia. However, there is a notable trend towards a higher sepsis rate.

Direct measurement of Coulomb-laser coupling.

The Coulomb interaction between a photoelectron and its parent ion plays an important role in a large range of light-matter interactions. In this paper we obtain a direct insight into the Coulomb interaction and resolve, for the first time, the phase accumulated by the laser-driven electron as it interacts with the Coulomb potential. Applying extreme-ultraviolet interferometry enables us to resolve this phase with attosecond precision over a large energy range. Our findings identify a strong laser-Coulomb coupling, going beyond the standard recollision picture within the strong-field framework. Transformation of the results to the time domain reveals Coulomb-induced delays of the electrons along their trajectories, which vary by tens of attoseconds with the laser field intensity.

Intravitreal Steroid Treatment for Uveitis Associated with Dabrafenib and Trametinib for Metastatic Cutaneous Melanoma.

Purpose: To report a case of bilateral retinal inflammation under long-term therapy with dabrafenib/trametinib for metastatic cutaneous melanoma.Methods: Retrospective chart review.Results: A 59-year-old patient with metastatic cutaneous melanoma diagnosed in 2004 under treatment with dabrafenib/trametinib since 2014 presented to our department with intraretinal hemorrhage and extrafoveal macula edema on the right eye and optic disc swelling on the left eye. The patient did not report visual complaints. After cessation of dabrafenib/trametinib and subconjunctival and intravitreal corticosteroid injections, optic disc swelling on the left eye recovered after 6 months. The macula edema on the right eye was treated with one intravitreal anti-VEGF (vascular endothelial growth factor) injection after encroaching upon the fovea 10 months after initial presentation. The final visual acuity was 20/20 on both eyes.Conclusion: Even after years of treatment with low dose dabrafenib/trametinib, ocular toxicity can develop. Such cases can respond well to intravitreal corticosteroids.

Sex Differences in High-Intensity Interval Training-Are HIIT Protocols Interchangeable Between Females and Males?

Background: High-intensity interval training (HIIT) is a well-established training modality to improve aerobic and anaerobic capacity. However, sex-specific aspects of different HIIT protocols are incompletely understood. This study aimed to compare two HIIT protocols with different recovery periods in moderately trained females and males and to investigate whether sex affects high-intensity running speed and speed decrement. Methods: Fifty moderately trained participants (30 females and 20 males) performed an exercise field test and were randomized by lactate threshold (LT) to one of two time- and workload-matched training groups. Participants performed a 4-week HIIT intervention with two exercise sessions/week: Group 1 (4 × 30,180 HIIT), 30-s all-out runs, 180-s active recovery and Group 2 (4 × 30,30 HIIT), 30-s all-out runs, 30-s active recovery. High-intensity runs were recorded, and speed per running bout, average speed per session, and speed decrement were determined. Blood lactate measurements were performed at baseline and follow-up at rest and immediately post-exercise. Results: Females and males differed in running speed at LT and maximal running speed determined during exercise field test (speed at LT, females: 10.65 ± 0.84 km h-1, males: 12.41 ± 0.98 km h-1, p < 0.0001; maximal speed, females: 14.55 ± 1.05 km h-1, males: 17.41 ± 0.68 km h-1, p < 0.0001). Estimated maximal oxygen uptake was ~52.5 ml kg-1 min-1 for females and 62.6 ml kg-1 min-1 for males (p < 0.0001). Analysis of HIIT protocols revealed an effect of sex on change in speed decrement (baseline vs. follow-up) in that females showed significant improvements only in the 4 × 30:30 HIIT group (p = 0.0038). Moreover, females performing the 4 × 30:30 protocol presented increased speed per bout and average speed per session at follow-up (all p ≤ 0.0204), while no effect was detected for females performing the 4 × 30:180 protocol. Peak blood lactate levels increased in all HIIT groups (all p < 0.05, baseline vs. follow-up), but males performing the 4 × 30:180 protocol showed no difference in lactate levels. Conclusions: If not matched for physical performance, females, but not males, performing a 4 × 30 HIIT protocol with shorter recovery periods (30 s) present increased average high-intensity running speed and reduced speed decrement compared to longer recovery periods (180 s). We conclude that female- and male-specific HIIT protocols should be established since anthropometric and physiological differences across sexes may affect training performance in real-world settings.

Yo-Yo Intermittent Recovery Level 1 Test for Estimation of Peak Oxygen Uptake: Use Without Restriction?

Purpose: This study analyzed the physiological response during Yo-Yo Intermittent Recovery Level 1 (YYIR1) test and re-test by in-field ergospirometry and time-series analyses of respiratory parameters. Methods: Ten moderately trained males (23.4 ± 2.01 years, VO2peak= 56.81 ± 10.75 mL·kg-1·min-1) completed three running trials including two separate YYIR1 tests and an independent maximal performance running test with time-series analyses of gas exchange parameters. Physiological response was assessed during all tests by determination of blood lactate levels (including calculation of individual lactate threshold), heart rate, oxygen consumption and respiratory exchange ratio (RER). Results: Modeling of YYIR1 test mean VO2 uptake kinetics over all participants revealed that VO2 increased rapidly after the individual lactate threshold (11.49 ± 0.66 km∙h-1 at 3.83 ± 0.42 mmol∙L-1) was reached with ~95% VO2peak at ~50% of the test duration (test, VO2 50%= 95.17 ± 8.74% of VO2peak; re-test, VO2 50%= 96.78 ± 7.04% of VO2peak). However, and despite identical YYIR1 test performance (1568 ± 364.6 m vs. 1568 ± 449.7 m, CV = 4.59%), mean VO2peak during YYIR1 test was 8.81 ± 5.6% higher than YYIR1 re-test (p = .027). Importantly, correlation of VO2peak with YYIR1 test performance was weak (R2 = 0.28, p = .115). Conclusions: We conclude that the YYIR1 test should not be used to estimate VO2peak. Further studies on direct determination of gas exchange parameters during different YYI test variants are warranted.

Correlation analysis of physical fitness and retinal microvasculature by OCT angiography in healthy adults.

Optical coherence tomography angiography (OCT-A) represents the most recent modality in retinal imaging for non-invasive and depth-selective visualization of blood flow in retinal vessels. With regard to quantitative OCTA measurements for early detection of subclinical alterations, it is of great interest, which intra- and extra-ocular factors affect the results of OCTA measurements. Here, we performed OCTA imaging of the central retina in 65 eyes of 65 young healthy female and male participants and evaluated individual physical fitness levels by standard lactate diagnostic using an incremental maximal performance running test. The main finding was that OCTA measurements of the foveal avascular zone (FAZ) area were associated with physical fitness. Using multivariate regression analysis, we found that running speed at the individual lactate threshold, a marker strongly associated with aerobic performance capacity, significantly contributed to differences in FAZ area (ß = 0.111, p = 0.032). The data indicates that smaller FAZ areas are likely observed in individuals with higher aerobic exercise capacity. Our findings are also of interest with respect to the potential use of retinal OCTA imaging to detect exercise-induced microvascular adaptations in future studies.

Shaping electron-hole trajectories for solid-state high harmonic generation control.

Solid-state high-harmonic generation (HHG) by an intense infra-red (IR) laser field offers a new route to generate coherent attosecond light pulses in the extreme ultraviolet regime. The propagation of the IR driving field in the dense solid medium is accompanied by non-linear processes which shape the generating waveform. In this work, we introduce a monolithic scheme in which we both exploit the non-linear propagation to manipulate a two color driving field, as well as generate high harmonics within a single crystal. We show that the resulting non-commensurate, bi-chromatic, generating field provides precise control over the periodicity of the HHG process. This control enables us to manipulate the spectral positions of the discrete harmonic peaks. Our method advances solid-state HHG spectroscopy, and offers a simple route towards tunable, robust XUV sources.

A three-step approach identifies novel shear stress-sensitive endothelial microRNAs involved in vasculoprotective effects of high-intensity interval training (HIIT).

Circulatory microRNAs (c-miRNAs) are regulated in response to physical activity and may exert anti-atherosclerotic effects. Since the vascular endothelium is an abundant source of c-miRNAs, we aimed to identify novel vasculoprotective exercise-induced c-miRNAs by the combined analysis of published endothelial miRNA array data followed by in vivo and in vitro validation. We identified 8 different array-based publications reporting 185 endothelial shear stress-regulated miRNAs of which 13 were identified in ≥3 independent reports. Nine miRNAs had already been associated with physical activity. Of the remaining novel miRNAs, miR-98-3p and miR-125-5p were selected for further analysis due to reported vasculoprotective effects. Analysis in two different 4-week high-intensity interval training (HIIT) groups (group 1 [n=27]: 4x30 s, group 2 [n=25]: 8x15 s; all-out running) suggested significantly elevated miR-98 and miR-125a-5p levels in response to acute exercise at baseline and at follow-up. Endothelial in vitro shear stress experiments revealed increased miR-125a-5p and miR-98-3p levels in medium of human umbilical vein endothelial cells at 30 dyn/cm2 after 20 and 60 min, respectively. Our results suggest that miR-98-3p and miR-125a-5p can be rapidly secreted by endothelial cells, which might be the source of increased c-miR-98-3p and -125a-5p levels in response to HIIT. Both miRNAs attenuate endothelial inflammation and may mediate vasculoprotective effects of physical exercise including HIIT.

Progressive high-intensity interval training (HIIT) is not superior to unmodified non-progressive HIIT in an uncontrolled setting.

BACKGROUND: High-intensity interval training (HIIT) is an important training component to improve aerobic and anaerobic exercise capacity. Higher HIIT workloads in general may generate additional effects on the improvement of exercise capacity, while missing adherence to more strenuous training regimes may affect training success. This study investigated if higher training workload generated by progressive HIIT (proHIIT) is superior to HIIT when used in an uncontrolled setting. METHODS: Thirty-four moderately trained females and males performed a 4-week training intervention with three exercise sessions per week. Participants were randomized into two HIIT groups using the individual lactate threshold at baseline: Group 1 (N.=17), HIIT, four runs at maximal speed (all-out) with 30 s active recovery (total: 48 runs), Group 2 (N.=17), proHIIT, 4 runs at maximal speed (all-out) with 30-second active recovery with one extra repetition every week (up to seven runs, for a total of 66 runs). An incremental field test protocol with standard blood lactate (LA) diagnostic and heart rate monitoring was used to access changes in exercise capacity. RESULTS: Overall, power output (running speed) at LA threshold (baseline LA+1.5 mmol/L) increased by +3.6% (P=0.004, effect size [ES] 0.38) after 4 weeks of HIIT. However, no significant between-group differences pre- vs post-intervention were detected. CONCLUSIONS: Our data suggest that proHIIT does not provide additional improvement of running speed at individual lactate threshold over HIIT in an uncontrolled setting.

Effects of high-intensity interval training on microvascular glycocalyx and associated microRNAs.

High-intensity interval training (HIIT) has been proposed to exert vasculoprotective effects. This study aimed to evaluate whether HIIT affects the microvasculature, including the endothelial glycocalyx barrier, and to identify associated microRNAs (miRNAs). Fifty healthy participants (23.1 ± 3.0 yr) performed a 4-wk 4 × 30-s all-out running HIIT. Sidestream dark-field imaging was performed at baseline and follow-up to detect changes of the sublingual microvasculature including the endothelial glycocalyx. Exercise parameters were determined by continuous running field test and documentation of high-intensity runs. miRNAs potentially associated with glycocalyx thickness were selected by structured literature search and blood samples for miRNA, and lactate measurements were drawn at baseline and follow-up HIIT. At baseline, a correlation between maximal exercise performance capacity and glycocalyx thickness (determined by perfused boundary region) was detected (P = 0.045, r = 0.303). Increased exercise performance at follow-up also correlated with glycocalyx thickness (P = 0.031, r = 0.416), and increased high-intensity sprinting speed was associated with an increased number of perfused vessels (P = 0.0129, r = 0.449). Literature search identified miR-143, -96-5p, and -24, which were upregulated by HIIT already at baseline and showed an association with peak blood lactate levels after sprints (all P < 0.05). Moreover, increased baseline miR-143 levels predicted increased glycocalyx thickness at follow-up (AUCmiR-143 = 0.92, 95% confidence interval, 0.81-1.0, P = 0.0008). Elevated resting miR-126 levels after the intervention were associated with cell-free versican mRNA levels. We conclude that HIIT induces changes in the endothelial glycocalyx of the microvasculature. Associated miRNAs such as miR-143 may represent a tool for monitoring early vasculoprotective adaptations to physical activity. NEW & NOTEWORTHY High-intensity interval training is known to improve health-related fitness in general and in lifestyle-induced chronic diseases. To visualize microvasculature structure and to detect exercise-induced changes, sublingual sidestream dark-field imaging microscopy was used, and circulating miRNAs were measured. This study shows that exercise-induced changes correlate with associated circulating miRNA, which might be useful for monitoring vasculoprotective effects. Furthermore, sidestream dark-field imaging may represent a sensitive tool for the early detection of exercise-induced systemic vascular changes.

Longer Work/Rest Intervals During High-Intensity Interval Training (HIIT) Lead to Elevated Levels of miR-222 and miR-29c.

Aim: MicroRNA-222 (miR-222) and miR-29c have been identified as important modulators of cardiac growth and may protect against pathological cardiac remodeling. miR-222 and -29c may thus serve as functional biomarkers for exercise-induced cardiac adaptations. This investigation compared the effect of two workload-matched high-intensity interval training (HIIT) protocols with different recovery periods on miR-222 and -29c levels. Methods: Sixty-three moderately trained females and males (22.0 ± 1.7 years) fulfilled the eligibility criteria and were randomized into two HIIT groups using sex and exercise capacity. During a controlled 4-week intervention (two sessions/week) a 4 × 30 HIIT group performed 4 × 30 s runs (all-out, 30 s active recovery) and a 8 × 15 HIIT group performed 8 × 15 s runs (all-out, 15 s active recovery). miR-222 and -29c as well as transforming growth factor-beta1 (TGF-beta1) mRNA levels were determined during high-intensity running as well as aerobic exercise using capillary blood from earlobes. Performance parameters were assessed using an incremental continuous running test (ICRT) protocol with blood lactate diagnostic and heart rate (HR) monitoring to determine HR recovery and power output at individual anaerobic threshold (IAT). Results: At baseline, acute exercise miR-222 and -29c levels were increased only in the 4 × 30 HIIT group (both p < 0.01, pre- vs. post-exercise). After the intervention, acute exercise miR-222 levels were still increased in the 4 × 30 HIIT group (p < 0.01, pre- vs. post-exercise) while in the 8 × 15 HIIT group again no acute effect was observed. However, both HIIT interventions resulted in elevated resting miR-222 and -29c levels (all p < 0.001, pre- vs. post-intervention). Neither of the two miRNAs were elevated at any ICRT speed level at baseline nor follow-up. While HR recovery was improved by >24% in both HIIT groups (both p ≤ 0.0002) speed at IAT was improved by 3.6% only in the 4 × 30 HIIT group (p < 0.0132). Correlation analysis suggested an association between both miRNAs and TGF-beta1 mRNA (all p ≤ 0.006, r ≥ 0.74) as well as change in speed at IAT and change in miR-222 levels (p = 0.024, r = 0.46). Conclusions: HIIT can induce increased circulating levels of cardiac growth-associated miR-222 and -29c. miR-222 and miR-29c could be useful markers to monitor HIIT response in general and to identify optimal work/rest combinations.

Robust enhancement of high harmonic generation via attosecond control of ionization.

High-harmonic generation (HHG) is a powerful tool to generate coherent attosecond light pulses in the extreme ultraviolet. However, the low conversion efficiency of HHG at the single atom level poses a significant practical limitation for many applications. Enhancing the efficiency of the process defines one of the primary challenges in the application of HHG as an advanced XUV source. In this work, we demonstrate a new mechanism, which in contrast to current methods, enhances the HHG conversion efficiency purely on a single particle level. We show that using a bichromatic driving field, sub-optical-cycle control and enhancement of the tunnelling ionization rate can be achieved, leading to enhancements in HHG efficiency by up to two orders of magnitude. Our method advances the perspectives of HHG spectroscopy, where isolating the single particle response is an essential component, and offers a simple route toward scalable, robust XUV sources.

Effects of high-intensity interval training on optic nerve head and macular perfusion using optical coherence tomography angiography in healthy adults.

BACKGROUND AND AIMS: High-intensity interval training (HIIT) has been identified to be efficient for increasing health-related fitness in general and in lifestyle-induced chronic diseases such as hypertension, obesity and metabolic syndrome. This study aimed to evaluate HIIT effects on optic nerve head (ONH) and macular perfusion in healthy adults using optical coherence tomography angiography (OCTA). METHODS: Fifty-eight healthy participants (22.0 ±â€¯2.02 years, 40 females (69.0%)) performed a 4-week HIIT with two exercise sessions/week: Group 1, 4 × 30 HIIT, running at maximal speed (all-out) for 4 × 30 s with 30 s active recovery, Group 2, 8 × 15 HIIT, running at maximal speed (all-out) for 8 × 15 s with 15 s active recovery. OCTA of the ONH and the macula was performed at baseline and follow-up to detect changes of the foveal avascular zone (FAZ). Flow density was evaluated in the superficial and deep plexus of the central macula, in the radial peripapillary capillary layer, the nerve head layer of the disc region and of the peripapillary region. RESULTS: The mean deep FAZ area and flow density of the superficial layer decreased by 14.00 ±â€¯13.02% and 1.26 ±â€¯3.20%, respectively, in response to overall HIIT (pre vs. post p <0.0001; p = 0.0041). The flow density of the nerve head layer in the peripapillary area showed an overall increase by 1.94 ±â€¯2.39% (pre vs post p < 0.0001). All other parameters showed no difference. CONCLUSIONS: HIIT may be performed to induce changes in ophthalmic measures such as FAZ and nerve head perfusion. OCTA imaging of the central retina and the ONH could represent a sensitive tool for the early detection of systemic vascular changes.

Self-probing spectroscopy of XUV photo-ionization dynamics in atoms subjected to a strong-field environment.

Single-photon ionization is one of the most fundamental light matter interactions in nature, serving as a universal probe of the quantum state of matter. By probing the emitted electron, one can decode the full dynamics of the interaction. When photo-ionization is evolving in the presence of a strong laser field, the fundamental properties of the mechanism can be signicantly altered. Here we demonstrate how the liberated electron can perform a self-probing measurement of such interaction with attosecond precision. Extreme ultraviolet attosecond pulses initiate an electron wavepacket by photo-ionization, a strong infrared field controls its motion, and finally electron-ion collision maps it into re-emission of attosecond radiation bursts. Our measurements resolve the internal clock provided by the self-probing mechanism, obtaining a direct insight into the build-up of photo-ionization in the presence of the strong laser field.

High visibility in two-color above-threshold photoemission from tungsten nanotips in a coherent control scheme.

In this article, we present coherent control of above-threshold photoemission from a tungsten nanotip achieving nearly perfect modulation. Depending on the pulse delay between fundamental ([Formula: see text]) and second harmonic ([Formula: see text]) pulses of a femtosecond fiber laser at the nanotip, electron emission is significantly enhanced or depressed during temporal overlap. Electron emission is studied as a function of pulse delay, optical near-field intensities, DC bias field and final photoelectron energy. Under optimized conditions modulation amplitudes of the electron emission of 97.5% are achieved. Experimental observations are discussed in the framework of quantum-pathway interference supported by local density of states simulations.