bluuebunny/crossref_metadata_2025 huggingface dataset:
Impact of Circadian Disruption on Female Mice Reproductive Function
Authors: Bahougne Thibault , Kretz Mathilda , Angelopoulou Eleni , Jeandidier Nathalie , Simonneaux Valérie
Published: February 2020

In female mammals, cycles in reproductive function depend both on the biological clock synchronized to the light/dark cycle and on a balance between the negative and positive feedbacks of estradiol, whose concentration varies during oocyte maturation. In women, studies report that chronodisruptive environments such as shiftwork may impair fertility and gestational success. The objective of this study was to explore the effects of shifted light/dark cycles on both the robustness of the estrous cycles and the timing of the preovulatory luteinizing hormone (LH) surge in female mice. When mice were exposed to a single 10-hour phase advance or 10-hour phase delay, the occurrence and timing of the LH surge and estrous cyclicity were recovered at the third estrous cycle. By contrast, when mice were exposed to chronic shifts (successive rotations of 10-hoursour phase advances for 3 days followed by 10-hour phase delays for 4 days), they exhibited a severely impaired reproductive activity. Most mice had no preovulatory LH surge at the beginning of the chronic shifts. Furthermore, the gestational success of mice exposed to chronic shifts was reduced, because the number of pups was 2 times lower in shifted than in control mice. In conclusion, this study reports that exposure of female mice to a single phase shift has minor reproductive effects, whereas exposure to chronically disrupted light/dark cycles markedly impairs the occurrence of the preovulatory LH surge, leading to reduced fertility.
Cardiac Biomarkers for the Prediction and Detection of Adverse Cardiac Events After Noncardiac Surgery: A Narrative Review
Authors: De Hert Stefan G. , Lurati Buse Giovanna A.
Published: February 2020

Yearly, more than 200 million people worldwide undergo noncardiac surgery, of whom about 5% will develop cardiovascular complications. Prevention, early recognition, and prompt treatment of these adverse cardiovascular events is therefore an important concern in perioperative medicine. The present narrative review aims to provide an overview and critical analysis of the currently available evidence on the role of biomarkers in perioperative cardiac risk assessment and monitoring of perioperative cardiac events before and after noncardiac surgery.
DnaJ-PKAc fusion induces liver inflammation in a zebrafish model of Fibrolamellar Carcinoma
Authors: de Oliveira Sofia , Houseright Ruth A. , Korte Benjamin G. , Huttenlocher Anna
Published: February 2020

Fibrolamellar Carcinoma (FLC) is a rare liver cancer that affects adolescents and young adults. Genomic analysis in FLC has revealed a 400 kB deletion in chromosome 19 that leads to a fusion protein, DNAJB1-PRKACA (DnaJ-PKAc) comprised of the first exon of the heat shock protein 40 (DNAJB1) and exons 2–10 of the catalytic subunit of protein kinase A (PRKACA). Here, we report a new zebrafish model of FLC induced by ectopic expression of zebrafish DnaJa-Pkaca (zfDnaJ-Pkaca) in hepatocytes that is amenable to live imaging of early innate immune inflammation. Expression of zfDnaJ-Pkaca in hepatocytes induces hepatomegaly and increased hepatocyte size. In addition, FLC larvae exhibit early innate immune inflammation characterized by early infiltration of neutrophils and macrophages into the liver microenvironment. Increased caspase-a activity was also found in the liver of FLC larvae, and pharmacological inhibition of TNFα and caspase-a decreased liver size and inflammation. Overall, these findings show that innate immune inflammation is an early feature in a zebrafish model of FLC and that that pharmacological inhibition of TNFα or caspase-1 activity might be targets to treat inflammation and progression in FLC.
Spatio-temporal control of post-Golgi exocytic trafficking in plants
Authors: Elliott Liam , Moore Ian , Kirchhelle Charlotte
Published: February 2020

A complex and dynamic endomembrane system is a hallmark of eukaryotic cells and underpins the evolution of specialised cell types in multicellular organisms. Endomembrane system function critically depends on the ability of the cell to (1) define compartment and pathway identity, and (2) organise compartments and pathways dynamically in space and time. Eukaryotes possess a complex molecular machinery to control these processes, including small GTPases and their regulators, SNAREs, tethering factors, motor proteins, and cytoskeletal elements. Whereas many of the core components of the eukaryotic endomembrane system are broadly conserved, there have been substantial diversifications within different lineages, possibly reflecting lineage-specific requirements of endomembrane trafficking. This Review focusses on the spatio-temporal regulation of post-Golgi exocytic transport in plants. It highlights recent advances in our understanding of the elaborate network of pathways transporting different cargoes to different domains of the cell surface, and the molecular machinery underpinning them (with a focus on Rab GTPases, their interactors and the cytoskeleton). We primarily focus on transport in the context of growth, but also highlight how these pathways are co-opted during plant immunity responses and at the plant–pathogen interface.
An Animal Trial on the Optimal Time and Intensity of Exercise after Stroke
Authors: Zhang Liying , Yang Xiaofeng , Yin Mingyu , Yang Huaichun , Li Lili , Parashos Alexandra , Alawieh Ali , Feng Wuwei , Zheng Haiqing , Hu Xiquan
Published: February 2020

Introduction

Although exercise is a safe, cost-effective, and therapeutic poststroke therapy, the proper time window and dosage of exercise are still unknown. We aim to determine the optimal combination of time window and intensity of exercise by assessing infarct volume, neurological recovery, and underlying mechanisms in middle cerebral artery occlusion rats.

Methods

The study contains two parts: the time-window and the dosage experiments. The time-window experiment assessed the effects of moderate-intensity exercise that was initiated at 24, 48, 72, 96 h and the control. In the dosage experiment, moderate and another two intensity exercise groups (low, high) were assessed. Forced wheel running was the exercise technique used. Infarct volume and neurological function (modified neurological severity scores [mNSS]) were measured. Inflammatory cytokines, cell death, and proliferation were further detected in the ischemic penumbra.

Results

The time window part revealed that neither infarct volume nor mNSS was reduced in the exercise group initiated at 24 h. The other three groups with exercise initiated after 24 h had reduced infarct volume and reduced mNSS but those outcomes do not differ from each other. In the dosage part, the low- and moderate-intensity groups with exercise initiated at 48 h were both better than the high-intensity group in terms of infarct volume and mNSS at 14 d; however, there was no statistical difference between these low and moderate groups. Exercise initiated at 24 h or high-intensity promoted proinflammatory cytokines and cell death.

Conclusions

Exercise at 24 h is harmful. Low- and moderate-intensity exercise initiated at 48 h poststroke appears to be the optimal combination for maximal functional recovery.
Hypoxic Exercise Training to Improve Exercise Capacity in Obese Individuals
Authors: CHACAROUN SAMARMAR , BOROWIK ANNA , VEGA-ESCAMILLA Y. GONZALEZ IGNACIO , DOUTRELEAU STÉPHANE , WUYAM BERNARD , BELAIDI ELISE , TAMISIER RENAUD , PEPIN JEAN-LOUIS , FLORE PATRICE , VERGES SAMUEL
Published: February 2020

Introduction

Combining exercise training with hypoxic exposure has been recently proposed as a new therapeutic strategy to improve health status of obese individuals. Whether hypoxic exercise training (HET) provides greater benefits regarding body composition and cardiometabolic parameters than normoxic exercise training (NET) remains, however, unclear. We hypothesized that HET would induce greater improvement in exercise capacity and health status than NET in overweight and obese individuals.

Methods

Twenty-three subjects were randomized into 8-wk HET (11 men and 1 woman; age, 52 ± 12 yr; body mass index, 31.2 ± 2.4 kg·m−2) or NET (eight men and three women; age, 56 ± 11 yr; body mass index, 31.8 ± 3.2 kg·m−2) programs (three sessions per week; constant-load cycling at 75% of maximal heart rate; target arterial oxygen saturation for HET 80%, FiO2 ~0.13, i.e., ~3700 m a.s.l.). Before and after the training programs, the following evaluations were performed: incremental maximal and submaximal cycling tests, measurements of pulse-wave velocity, endothelial function, fasting glucose, insulin and lipid profile, blood NO metabolites and oxidative stress, and determination of body composition by magnetic resonance imaging.

Results

Peak oxygen consumption and maximal power output increased significantly after HET only (peak oxygen consumption HET + 10% ± 11% vs NET + 1% ± 10% and maximal power output HET + 11% ± 7% vs NET + 3% ± 10%, P < 0.05). Submaximal exercise responses improved similarly after HET and NET. Except diastolic blood pressure which decreased significantly after both HET and NET, no change in vascular function, metabolic status and body composition was observed after training. Hypoxic exercise training only increased nitrite and reduced superoxide dismutase concentrations.

Conclusions

Combining exercise training and hypoxic exposure may provide some additional benefits to standard NET for obese individual health status.
Cardiovascular Drift and Maximal Oxygen Uptake during Running and Cycling in the Heat
Authors: WINGO JONATHAN E. , STONE TORI , NG JASON
Published: February 2020

Introduction

Greater cardiovascular (CV) drift occurs during cycling compared to running in temperate conditions. CV drift also corresponds to proportional reductions in maximal oxygen uptake (V˙O2max) during heat stress. Whether exercise mode differentially affects CV drift—and accompanying declines in V˙O2max—during heat stress is uncertain. The purpose of this study was to test the hypothesis that a greater magnitude of CV drift, accompanied by a greater decrement in V˙O2max, occurs during cycling compared to running in hot conditions.

Methods

7 active men (mean ± SD; age = 25 ± 6 yr, percent body fat = 11.9% ± 2.4%) completed a control graded exercise test (GXT) on a cycle ergometer and treadmill. Then on separate, counterbalanced occasions they completed 15 or 45 min of cycling or running at 60% V˙O2max in 35°C, immediately followed by a GXT to measure V˙O2max (4 trials total). The separate 15- and 45-min trials were designed to measure CV drift and V˙O2max over the same time interval.

Results

Heart rate increased 19% and 17% and stroke volume decreased 20% and 15% between 15 and 45 min during running and cycling, respectively, but modes were not different (all P > 0.05). Despite a 1.8°C larger core-to-skin thermal gradient during running, decrements in V˙O2peak were not different between exercise modes (95% CI for difference in change scores between 15 and 45 min: −0.2, 0.3).

Conclusions

CV strain (indexed as CV drift) during prolonged exercise in the heat corresponds to reduced V˙O2max, irrespective of exercise mode or the thermal gradient. As such, the upward drift in heart rate associated with CV drift reflects increased relative metabolic intensity (%V˙O2max) during prolonged cycling or running in the heat.
Real-time markerless tumour tracking with patient-specific deep learning using a personalised data generation strategy: proof of concept by phantom study
Authors: Takahashi Wataru , Oshikawa Shota , Mori Shinichiro
Published: February 2020

Objective:

For real-time markerless tumour tracking in stereotactic lung radiotherapy, we propose a different approach which uses patient-specific deep learning (DL) using a personalised data generation strategy, avoiding the need for collection of a large patient data set. We validated our strategy with digital phantom simulation and epoxy phantom studies.

Methods:

We developed lung tumour tracking for radiotherapy using a convolutional neural network trained for each phantom’s lesion by using multiple digitally reconstructed radiographs (DRRs) generated from each phantom’s treatment planning four-dimensional CT. We trained tumour-bone differentiation using large numbers of training DRRs generated with various projection geometries to simulate tumour motion. We solved the problem of using DRRs for training and X-ray images for tracking using the training DRRs with random contrast transformation and random noise addition.

Results:

We defined adequate tracking accuracy as the percentage frames satisfying <1 mm tracking error of the isocentre. In the simulation study, we achieved 100% tracking accuracy in 3 cm spherical and 1.5×2.25×3 cm ovoid masses. In the phantom study, we achieved 100 and 94.7% tracking accuracy in 3 cm and 2 cm spherical masses, respectively. This required 32.5 ms/frame (30.8 fps) real-time processing.

Conclusions:

We proved the potential feasibility of a real-time markerless tumour tracking framework for stereotactic lung radiotherapy based on patient-specific DL with personalised data generation with digital phantom and epoxy phantom studies.

Advances in knowledge:

Using DL with personalised data generation is an efficient strategy for real-time lung tumour tracking.
Correlation between ultrasound consolidated score and simple endoscopic score for determining the activity of Crohn’s disease
Authors: Liu Chang , Ding Shi-Si , Zhang Kun , Liu Lin-Na , Guo Le-Hang , Sun Li-Ping , Zhang Yi-Feng , Sun Xiao-Min , Ren Wei-Wei , Zhao Chong-Ke , Li Xiao-Long , Wang Qiao , Xu Xiao-Rong , Xu Hui-Xiong
Published: February 2020

Objectives:

The aim of this study was to develop an ultrasound consolidated score (UCS) in determining the activity of Crohn’s disease (CD) and evaluate it with reference to simple endoscopic score (SES).

Methods:

From June 2014 to June 2017, 66 patients with CD were retrospectively enrolled in this study. Each patient underwent endoscopy and transabdominal ultrasound (US) examination. The morphological symmetry, echogenicity of bowel wall, bowel wall layer structure, echogenicity of peri-bowel fat, bowel wall thickness (BWT), and Limberg type on power Doppler US were assessed with transabdominal US, and an UCS scoring system was developed based on these characteristics. Endoscopic results were used as the reference standard and SES was calculated to determine the CD activity. Receiver operating characteristic curve analysis was performed to assess the diagnostic performance for determining CD activity and the correlation between UCS and SES was assessed using Spearman correlation analysis.

Results:

330 intestinal segments in 66 patients were included. The UCS of the segments in the remission phase ranged from 3.0 to 9.0 (mean, 3.6 ± 0.9) whereas in the active phase from 3.0 to 20.0 (mean, 10.6 ± 4.0) (p < 0.001). The cut-off value of UCS was 6. The associated area under ROC curve, sensitivity, specificity, positive predictive value, negative predictive value, and accuracy were 0.980, 88.3%, 95.5%, 93.8%, 91.3%, and 92.3%, respectively. The correlation coefficient between UCS and SES was 0.90, which was higher than the correlation coefficient of 0.83 between BWT and SES.

Conclusions:

The newly developed UCS with transabdominal US has a good performance and potentially provides an effective alternative for evaluating the activity of CD.

Advances in knowledge:

UCS is an effective method to evaluate the activity of CD because it provides comprehensive information of the disease. Therefore, it could be employed as an alternative for diagnosis of CD.
Physical origins of the optical nonlinearities of materials: an overview
Authors: Tang C. L.
Published: February 2020

Key considerations in the search for new nonlinear optical crystals for UV applications and in the determination of the physical origins of the nonlinear refractive indices of laser glasses and organic liquids using femtosecond interferometry are reviewed.
Compact holmium laser range finder
Authors: Payne M. J. P. , Evans H. W. , Clay R. A.
Published: February 2020

Lasers emitting at wavelengths of >1.4 μm present a much reduced ocular hazard compared with shorter wavelength devices because absorption of radiation by the water of the eye prevents high intensities due to focusing at the retina. The holmium:YLF (YLiF4) laser generates a wavelength of 2.08 μm and thus falls in the class of eye-safe lasers. Corneal damage may still occur, but with a threshold of 3.5 J/cm2 for O-switched pulses, this is not a problem with the low-energy output pulses from our range finder.
Multiphoton Infrared chemistry: an industrial perspective
Authors: Hall R. B.
Published: February 2020

Although we continue to use laser chemistry to obtain a wealth of fundamental information, in terms of applications of lasers in chemical industry, are there opportunities beyond isotope separation? There are few, if any, laser-based processes on the immediate horizon; however, several areas hold promise. Several new directions in laser chemistry at Exxon and elsewhere will be discussed.
Phase synchronization of CO2 lasers with application in Costas-type hemodyne receivers
Authors: Leeb Walter R. , Scholtz Arpad L. , Philipp Heinz K. , Bonek Ernst
Published: February 2020

As in the microwave region, the most sensitive communication receivers for the optical region will be realized by employing the homodyne principle. This requires mixing the received signal with a coherent phase-synchronized local oscillator laser. Under contract with the European Space Agency we have investigated theoretically and experimentally the utilization of a phase-locked loop (PLL) for carrier regeneration at the CO2 laser wavelength of 10 μm.
New optically pumped lasers
Authors: Wellegehausen B.
Published: February 2020

Optical excitation of suitable materials with pulsed or cw lasers is a powerful method for the development of new laser systems. In the past few years interesting molecular laser systems such as the cw dimer lasers1 or photodissociation lasers2 have been obtained by this technique. This paper reports on new optically pumped lasers and new possible systems.
Remote sensing using lasers
Authors: Fredriksson K. , Svanberg S.
Published: February 2020

The rapid development of laser systems and advanced electronics has permitted the introduction of efficient remote-sensing techniques for air and sea based on applied laser spectroscopy.1,2 The interaction between laser light and molecules is monitored as absorption, fluorescence, or Raman scattering. As platforms for remote sensors, trucks, airplanes, or satellites can be used. For the atmosphere both meteorological parameters and pollution levels can be measured.
Nonlinear optics in liquid suspensions of submicron particles
Authors: Ashkin A. , Smith P. W.
Published: February 2020

Liquid suspensions of submicron particles have been used as a new type of artificial nonlinear optical Kerr medium. Experiments were performed on cw degenerate four-wave mixing and cw self-focusing and self-trapping using such media. The nonlinearities of these media arise from the physical motion of the particles due to radiation pressure forces.1–3 These light forces either pull particles into or out of regions of high light intensity depending on whether their index of refraction is greater or less than that of the surrounding liquid. This results in particle density changes which increase the local index of refraction in regions of high light intensity. The effective nonlinear coefficient n2 describing this intensity dependent refractive index is large (~105 that of CS2) with a response time of milliseconds to seconds governed by the viscosity of the liquid.
New stable color-center lasers using metal-doped alkali halides
Authors: Gellermann W. , Koch K. , Luty F.
Published: February 2020

Two types of color-center systems have previously been successfully tested and applied as tunable IR laser materials.
High peak power performance of alexandrite
Authors: Siebert D. R. , Barrett J. J. , Walling J. C. , Cullison M. G. , Schuh G. L.
Published: February 2020

Alexandrite (BeAl2O4:Cr3+) is a broadly tunable solid-state laser material with an RT emission cross section at 750 nm of 7 × 10−21 cm2,1 some 100 times smaller than that of YAG:Nd3+ and 4 times smaller than that of ruby (Al2O3:Cr3+). The lower emission cross section of alexandrite has generally limited the peak power available from Q-switched pulses.
Optical beam phase-conjugation by nonlinear optical effects: the first decade
Authors: Hellwarth R. W.
Published: February 2020

We review the nature, physics, and applications of optical beam phase-conjugation by nonlinear optical effects. The history of the subject now spans a decade. In its commonest form, this process of optical beam phase-conjugation generates, nearly instantaneously, a time-reversed replica of a complex monochromatic beam throughout a large portion of space. Because a beam retracing its path through an aberrator reemerges in its original unaberrated pattern, phase-conjugation can be used to correct unwanted aberrations arising in, for example, beam propagation through laser amplifiers.
Phase-conjugation, image processing, and image compensation in photorefractive crystal
Authors: Yariv Amnon
Published: February 2020

Many of the attractive applications of phase- conjugate optics1 and, more generally, of the field of four-wave mixing depend on the availability of efficient nonlinear (mixing) materials. This is especially true in applications involving real-time image processing.2,3
Pulsed xenon chloride laser annealing of sulfide films on silicon
Authors: Reehal H. S. , Gallego J. M. , Edwards C. B.
Published: February 2020

Zinc sulfide is a promising material for electroluminescent devices covering the entire visible range o1 the spectrum.1 In ion-implanted silicon, the pulsed laser annealing technique overcomes common problems associated with conventional thermal annealing2 such as dopant segregation and partial removal of lattice damage. Work on the II-IV semiconductors, however, is at an early stage.
Optical properties of ion-implanted Si by cw CO2 laser annealing
Authors: Li Yuan-Heng
Published: February 2020

We have experimentally investigated variations in ellipsometric parameters ψ, Δ, reflectivity R, surface sheet resistance ρ with radiation time by cw CO2 laser annealing (Fig. 1). The output power of the CO2 laser was 40 W and the beam diameter ~8 mm; 150-keV As+ ions were implanted at a dose of 1 × 1016/cm2 for 6-8 Ω 1 cm (100) P-type Si. The experiments showed that ψ,Δ,R,ρ did not obviously change in the initial stage but sharply decreased to the corresponding values of the crystal silicon after 5-sec radiation.
Continuous-wave optically pumped 12-μm NH3 laser
Authors: Rolland C. , Reid J. , Garside B. K.
Published: February 2020

Over the past decade, optical pumping of molecular gases has become a very successful method of generating laser radiation in the mid-IR and far-IR regions. Many hundreds of optically pumped far-IR lasers (cw and pulsed) now cover the spectral range between 34 μm and 2 mm. However, at shorter wavelengths optically pumped mid-IR lasers only operate on a pulsed basis. Mid-IR lasers are particularly attractive for their potential application in fields such as laser photochemistry or laser isotope separation.
Two-wavelength lidar techniques for the measurement of atmospheric density profiles
Authors: Korb C. Laurence , Weng Chi Y.
Published: February 2020

Density is one of the basic atmospheric parameters, and it is important for determining such diverse properties as heating rates for reentry vehicles and atmospheric transmission characteristics. This paper discusses a new two-wavelength lidar technique for the measurement of atmospheric density profiles. The technique uses a differential absorption lidar system with differential ranging. A measurement of atmospheric density is obtained using two frequencies.
Holographic and diffraction scannig for UPC label readers
Authors: Cheng Charles C. K.
Published: February 2020

This paper describes the design and prototype of a 2-D holographic diffraction and scanning system1 for a Universal Products Code (UPC) label reader for supermarket point-of-sales electronic check-out applications. The scanner’s optical fabrication and arrangement are simple compared with conventional UPC scanners. The holographic diffraction scanner consists of a 6-mm thick 13-cm diam glass disk on which a number of lenslike holograms are recorded along the circumferences of two concentric rings.
Compact optical pickup for 3-D recording and playing system
Authors: Saimi Tetsuo , Yoshizumi Keiichi , Okino Yoshi-Hiro
Published: February 2020

Optical recording techniques promise a number of important advantages due to the high-storage capacity of 1010 bits and ease of handling. Recently many techniques have been published for small size optical pickups. However, it seems these are not sufficient for a 3-D optical pickup system for a high data rate such as video signals. A 3-D optical recording and playing pickup needs several properties.
Attenuation of visible and IR radiation by rain
Authors: Winchester L. W. , Gimmestad G. G. , Lee S. M.
Published: February 2020

The attenuation of radiation at 0.6328 μm and in the bands between 3 and 5 μm and between 8 and 12 μm has been measured as a function of rain rate. The transmission measurements are made over a 1-km folded path using a He–Ne laser transmissometer and a Barnes model 14-708 IR transmissometer. A fully automated weather station is used to collect all relevant weather parameters. Ail measurements are averaged over 1-min intervals and recorded digitally.
Microoptical spatial filtering for optical inspection
Authors: Cielo P. , Lapierre J.
Published: February 2020

The inspection of surfaces is an important aspect of nondestructive evaluation of industrial materials. Optical inspection methods are preferable to other methods, such as liquid penetrants or eddy-current techniques, because of their rapidity, noncontact nature, and ease of scanning, which make optical techniques particularly suitable to automatic detection of surface characteristics. The basic problems faced by optical inspection systems are related to surface scattering properties, speckle, alignment considerations, and changes in surface reflectivity.1
Two-photon laser instability
Authors: Ovadia Shlomo , Sargent Murray
Published: February 2020

Now that two-photon laser oscillation has been observed,1 the theory of the device is more relevant than ever. It is well-known that single-photon homogeneously broadened lasers can undergo chaotic single-wavelength instabilities.2 Specifically, the nonlinear polarization causes more than one frequency to have net gain and to be resonant for a single wavelength in the cavity. The calculation can be based on the gain coefficient for side modes that straddle a centrally tuned strong mode.
Automated immunofluorescent analysis of peripheral bleed cells by light scatter and double fluorophore label methods
Authors: Hansen W. P. , Hoffman R. A. , Ip S. , Healy K.
Published: February 2020

An extremely rapid flow cytometric method identifies leucocyte classes by a combination of low angle and wide angle light scatter signals, together with two wavelength bands of fluorescent emission from monoclonal antibody surface markers.
Reflectance and beam angle variations under de magnetic field for human blood at the Ar+laser line
Authors: Sato Heihachi , Hayashi Hidenori , Totsuka Takamasa , Sugiyama Mitsugu , Tsughiya Shuji
Published: February 2020

At the Ar+ laser line both variations of reflectance .ΔR and beam angle Δθ, with and without the de magnetic field, were measured for human blood sampled from patients with various diseases. Statistical analysis on both ΔR and Δθ provides useful information for distinguishing whether the sample is malignant or benign.
Microsurgical anastomosis using a CO2 laser: a preliminary report
Authors: Freeman R. H. , Gordon J. A. , Thomson C. B.
Published: February 2020

Lasers have been used in surgery for several years. The introduction of the laser into medicine is recognized as an advance in technology which has resulted In a better surgical technique to control bleeding (coagulation), resect or excise large tumors (gynecology, neurosurgery, gastroenterology), restore sight to the blind eye (opthalmology), and remove large cancers quickly where otherwise large amounts of blood loss and spreading of the disease are expected. The laser (primarily at high powers) has been utilized to decrease surgical time and decrease foreign body reaction.
Directly switched ultrafast laser-diode sources tor the visible and near IR spectral regions
Authors: Park R. E. , Garside B. K. , Gouin F. L. , Godfrey L. A.
Published: February 2020

High-speed sources and photodetectors in the visible and near IR are essential in applications such as ultra-high-speed optical communications sytems, fiber-optic system characterization, picosecond photochemistry, and laser ranging. Opto-Electronics has developed a line of very high-speed detectors with rise times as fast as 25 psec for selected devices. To complement these detectors it is necessary to have sources having pulse lengths in the 10-100-psec range which are reliable and simple to operate.
Numerical optical temporal integrator using a residue arithmetic representation: design and discussion
Authors: Habiby Sarry F. , Collins Stuart A.
Published: February 2020

This paper deals with numerical optical computing using the residue arithmetic representation. Specifically, a scheme for performing an addition operation given in the literature1 is extended and applied to the design of a particular device, a numerical temporal integrator. The temporal integrator is a device that keeps a running sum of a sequence of numbers which come in one after another. Two independent operations are needed to achieve this goal, a sum operation and a hold operation providing storage. The sum operation uses the interference of two plane waves on the input of a Hughes liquid crystal light valve. In the square law detection process the two spatial frequencies are added. The hold operation is formed from a feedback summer. Over 2000 such devices operating in parallel are potentially possible on a standard Hughes liquid crystal light valve.
YAG laser welding of dissimilar materials
Authors: Jones Marshall
Published: February 2020

The difficulties of joining materials with different melting points and other thermal properties have precluded widespread use of direct welds of dissimilar metals. The thermal conditions associated with pulsed laser heating simplify this problem.
Use of double-stream relativistic electron beams in tree-electron lasers
Authors: Piestrup M. A.
Published: February 2020

The two-stream instability problem has been studied in plasma physics for over 30 years and has been used to generate microwaves of centimeter wavelengths. The device, independently devised and constructed by Haeff1 and Pierce,2 was called an electron wave tube or two-stream amplifier and consists of two low-energy electron streams interacting to give an increasing space-charge wave without field supporting structure. The latter fact is clearly an advantage for submillimeter and shorter wavelength sources, since conventional microwave devices require circuit elements whose dimensions are of the order of the generated wavelength.
Analysis of tree-electron laser mode structure
Authors: Quimby D. C. , Slater J. M.
Published: February 2020

The mode structure of a tapered wiggler free-electron laser (FEL) stable oscillator is investigated using an axisymmetric physical optics code which accounts for diffraction, nonuniform gain media, refraction, and arbitrary mirror configurations and reflectivities. Figure 1 shows the evolution of TEM10 and TEM10 mode content, as a plane polarized optical beam is circulated in symmetric resonators of various lengths. Each cavity has mirrors of radius 1.8 w/ located at the ends of the wiggler, where w is the 1/e amplitude point for the initial 0-0 pump beam.
Intra-abdominal uses of the CO2 laser in gynecologic surgery
Authors: Baggish Michael S.
Published: February 2020

Although the CO2 laser has had extensive application in gynecology and several reports describing its therapeutic effects have appeared in contemporary literature, there are very few publications about the intra-abdominal use of this Instrument. Initial studies employing the CO2 laser for experimental oviductal anastomosis and adhesiolysis were presented in 1979 at the International Society for Laser Surgery Congress in Graz, Austria. The results of animal and human microsurglcal techniques on the uterine tube utilizing the CO2 laser have only recently appeared in current gynecological literature.
Carbon dioxide and HF laser-induced decomposition of methanol
Authors: Evans D. K. , McAlpine R. D. , Goodale J. W. , Adams H. M.
Published: February 2020

Methanol absorbs HF laser radiation in the O-H stretching mode and CO2 laser radiation in its C-O stretching mode. Thus multiphoton absorption (MPA) and multiphoton decomposition (MPD) experiments determining the effect on product yields of irradiating different modes of the same small molecule are possible for methanol. Such a comparison has been reported previously.1 However, another study of CO2 laser-induced MPD2 disagreed with the product ratios reported.
Infrared-multiphoton absorption: a powerful technique for preparing ensembles of highly vibrationally excited molecules
Authors: Barker John R. , Golden David M. , Rossi Michel J.
Published: February 2020

Infrared-multiphoton absorption is a powerful technique for preparing ensembles of exicted molecules that can be used in energy-transfer experiments and in studies of chemical reactivity. To take full advantage of this technique, the ensembles of excited molecules must be adequately characterized both theoretically and experimentally. Toward this end, we have performed experiments to investigate unimolecular reactions, intensity effects in the absorption process, and the IR fluorescence of the excited molecules.
Theoretical treatment of multiple photon excitation in SF6
Authors: Galbraith H. W. , Ackerhalt J. R.
Published: February 2020

Recent spectroscopic work on the 3v3 band of SF6 has yielded two fundamental results important to our understanding of multiple photon absorption in SF6:(1) vibrational splittings are large and dominie the multiple photon spectrum at low temperature; (2) the molecular quasi-continuum lies above the 3v3 level in energy. The new picture of the discrete levels shows that multiple photon resonances persist up to at most ~10 photons within the v3 ladder, indicating that the molecular quasi-continuum is not needed to explain multiple photon absorption until high levels in the molecule are attained.
Measurements of temperature and N2 concentration in a turbulent diffusion flame using She CARS technique
Authors: Goss L. P. , Trump D. D. , Switzer G. L.
Published: February 2020

The study of turbulent combustion on a fundamental level requires detailed spatially resolved information on the instantaneous values of a number of scalar quantities acquired simultaneously. The goal of this study is to measure these quantities [single and joint probability density functions (pdf)] using nonperturbing experimental techniques in a relatively simple turbulent flame.
Compact CO2 laser with transverse rf excitation
Authors: Hugel H. , Schock W.
Published: February 2020

The design and operation of a subsonic flow 2.5-kW CO2 laser with transverse rf excitation are reported. Particular emphasis is given to two methods of power incoupling, i.e., the use of either metallic or dielectric electrodes.
Short-wavelength direct-drive laser fusion research: a status report
Authors: Soures J. M.
Published: February 2020

Laser-driven fusion is one of the most technologically challenging and potentially most useful applications of high powered lasers. The major physics problems that must be overcome to demonstrate the scientific feasibility of laser fusion are: (a) coupling of the laser energy to a target without generating energetic electrons that can cause fuel preheat and fast ion losses; (b) conversion of a significant part of the absorbed laser energy to hydrodynamic motion, via ablation, while at the same time maintaining a high degree of drive uniformity; (c) compression of deuterium-tritium (DT) fuel to densities in excess of 1000X liquid DT densities under conditions where the disruptive effects of hydrodynamic instabilities must be minimized; (d) achievement of thermonuclear Ignition conditions in small DT fuel cores.
Optically pumped mode-locked InGaAsP lasers
Authors: Putnam R. S. , Roxlo C. B. , Salour M. M. , Groves S. H. , Plonko M. C.
Published: February 2020

We report the first optically pumped mode-locked semiconductor laser operating at wavelengths longer than 1.0 µm. Laser operation has been achieved in two separate compositions of In1−x GaxAsyP1−y at 1.1 and 1.2 µm with x = 0.20, y = 0.4 and x = 0.24, y = 0.55, respectively. Continuous wave operation was obtained with more heating problems than were observed in CdS1 and CdSSe2 due to relatively poor thermal conductivity in the quaternary layer. To reduce this effect during pulse width and spectral measurements, the pump beam was mechanically chopped.
Third harmonic generation and multiphoton ionization in carbon monoxide
Authors: Glownia James H. , Sander Robert K.
Published: February 2020

Third harmonic generation (THG) in atomic vapor is a well-known source of VUV light.1 Because the third-order susceptibility is low, the pump light intensity must be high, and often competing effects such as multiphoton ionization (MPI) and dielectric breakdown occur. Additionally, for molecules dissociation may also occur. Thus molecules have only rarely been studied for this purpose.2 Carbon monoxide (CO), however, is an attractive candidate for THG due to its high dissociation energy, 11.11 eV, and Ionization potential, 14.01 eV. For the v′ = 0, 1, and 2 members of the A1∏-X1∑ progression, a 3-photon resonance is present below the dissociation energy, and 6 pump photons are required to reach the ionization potential.
Laser autoionization mass spectroscopy: the potential for single-atom detection
Authors: Nogar N. S. , Miller C. M.
Published: February 2020

We describe a single-step photoionization scheme, based on the use of autoionizing resonances, which is used in the analysis of ytterbium nitrate samples. The cross section for the 6s2 1S0→5d6p 3D transition is 10−16 cm2, allowing optical saturation (~100 % ionization) over a rather large focal volume of ≳ 10−2 cm3 as well as providing elemental selectivity in the ionization process.
Noncontact optoacoustic monitoring: flow measurements and other applications
Authors: Tam A. C. , Zapka W.
Published: February 2020

Acoustic propagation velocity v in a fluid depends on flow-velocity v
f
vectorially and temperature T. Measuring v in two suitable directions provides a good method for determining v
f
and T simultaneously. This is particularly valuable in gas flows, where the other noncontact flow determination method by light-scattering technique (laser Doppler velocimetry) is difficult because of the negligible Rayleigh scattering efficiencies of gases in the absence of particles (e.g., smoke particles or oil droplets are usually added to the gas to observe light scattering). Furthermore, our noncontact acoustic technique is also applicable to hostile environments (flames, discharges, etc.), where background luminescence may pose severe limitations on light-scattering measurements.
Flow visualization in supersonic air with the resonant Doppler velocimeter
Authors: Zimmermann M. , Cheng S. , Miles R. B.
Published: February 2020

We report the first use of the resonant Doppler velocimeter (RDV) for complete flow field visualization in a supersonic airflow. The RDV is a new nonintrusive diagnostic tool which takes advantage of laser absorption effects to measure the velocity, temperature, and pressure of a flowing gas. In this manner it eliminates particle lag, which is characteristic of standard laser Doppier velocimetry. Tracer atoms or molecules are seeded into the flowing gas under investigation and are excited by an intersecting laser beam. Since the gas is moving, the absorption frequency is Doppler shifted. This technique may be used for flow visualization. An expanded narrow linewidth laser beam may be tuned so that regions in the flow with a specific velocity component fluoresce brightly enough to be seen with the naked eye.
Holographic laser-Doppler optics for high spatial resolution measurements
Authors: Stojanoff C. G. , Windeln W.
Published: February 2020

The classic laser-Doppler signal has a pronounced Gaussian envelope. This type of signal limits the useful demodulation time to the central portion of the signal where the amplitude is large. The problem could be alleviated by tailoring the intensity distribution throughout the measuring volume. It is well-known that the illuminating function and its image in the focal plane form a Fourier transform pair. In this case, if one wants to obtain a square wave intensity distribution in the object plane, the illumination function should be of the form sin x/x. However, an illuminating function of this type is not easy to produce.
Development of a fiber-optic laser-Doppler flow monitor
Authors: Schmalfuss H. , Seger G.
Published: February 2020

Under contract with the German Federal Ministry for Research and Technology, Battelle-Frankfurt developed a fiber-optic flowmeter operating according to the principle of two-beam laser-Doppler anemometry. The function of this apparatus is to monitor slowly flowing inorganic and organic solvents during the reprocessing of nuclear fuels.
Small-scale hollow-cathode multicolor metal-ion lasers
Authors: Tsuda H. , Piper J. A.
Published: February 2020

The development of hollow-cathode metal-ion lasers has attracted considerable attention recently because of their ability to generate multiwavelength output in the visible with comparatively good power and low noise. However, hollow-cathode laser tubes suffer problems arising from difficulties in control of metal vapor pressure, discharge instability, and cathode erosion, and few attempts have been made to develop practical devices.
Polarized cw Nd:YAG laser using a slab geometry
Authors: Kane T. J. , Eggleston J. M. , Byer R. L.
Published: February 2020

When a solid-state laser is excited at high average power, temperature differences within the laser material create stresses. These stresses along with the residual stress remaining from crystal growth make it difficult to extract efficiently polarized output from high-power Nd:YAG lasers using the traditional rod geometry. We demonstrated that both thermal and residual birefringence can be eliminated by using a geometry in which the laser beam zigzags through the laser material. Our observations and calculations indicate that it is possible to build an efficient 100-W Nd:YAG laser with polarized output and that it is not necessary to use stress-free Nd:YAG material.
Signal processing applications of guided-wave optical devices
Authors: Taylor Henry F.
Published: February 2020

For several years signal processing has been recognized as an important application area for guided-wave optical technology along with communications and sensing. This paper discusses the design and performance of signal processing devices using single-mode integrated optics and fiber-optics components. Potential advantages over conventional techniques and some typical applications are indicated.
Ablation pressure and ablative compression
Authors: Key M. H.
Published: February 2020

The study of laser plasma interactions and of dense plasma produced by laser compression is both interesting basic physics and the basis on which laser fusion concepts can be developed. University researchers in the U.K. have established a Central Laser Facility at the SERC Rutherford Appleton Laboratory where the laser has been specifically developed as a versatile research facility for work in this field.
Laser plasma interaction experiments at 1.064, 0.532, and 0.355µm
Authors: Campbell E. M.
Published: February 2020

The effect of laser wavelength on laser-plasma coupling is one of the critical issues facing the laser driven inertial confinement fusion community. Advantages of using lasers with output wavelength of <1µm, such as enhanced absorption and hydrodynamic efficiency, reduction in parametric instabilities, and corresponding suprathermal electron generation, have long been predicted theoretically. However, the details of and competition between the important processes occurring in the laser plasma interaction are not known well, and thus quantitative scaling with the driver wavelength is extremely uncertain.
Wide-beam optical communications using semiconductor diodes
Authors: Majumdar Arun K. , Fortescue George
Published: February 2020

Optical communication systems design considerations and experimental results are presented. The emphasis of this work is the use of wide divergent beams1 eliminating the need for gimbaled pointing and tracking mountings.
Earth observations using radar and electrooplics systems on board the Space Shuttle
Authors: Elachi Charles
Published: February 2020

In Nov. 1981, the shuttle Columbia carried its first scientific payload into earth orbit. This payload included a shuttle image radar (SIR-A) which acquired images over numerous regions around the world.
Lasers applications In the automotive industry
Authors: Gara Aaron D.
Published: February 2020

High technology tools, such as the lasers, are being explored by the automotive industry particularly in the areas of productivity, quality control, and product development.
Laser processing of microelectronic devices
Authors: Osgood Richard M.
Published: February 2020

Laser sources have recently been investigated for use in a number of diverse processing applications for microelectronics.
Theory and measurement of degenerate four-wave mixing in a resonant three-level absorber
Authors: Watkins D. E. , Phipps G. R.
Published: February 2020

The study of degenerate four-wave mixing (DFWM) in the doped alkali halide KCI:KReO4 was prompted by the observation that this material behaves like an ideal, homogeneously broadened two-level saturable absorber at CO2 laser wavelengths,1 for which a simple theory of DFWM exists.2
Noise cancellation in pyroeiectric self-scanning IR detector arrays
Authors: Roundy Carlos B.
Published: February 2020

Solid-state pyroelectric IR detector arrays have provided a long-awaited breakthrough in instrumentation for IR imaging. Profiling of IR laser beams can now be done with wide dynamic range, high linearity and uniformity, and high spatial resolution.
Propagation-induced depth measurement biases for airborne laser hydrography
Authors: Guenther Gary C. , Thomas Robert W. L.
Published: February 2020

Of the many error sources associated with airborne laser hydrography, one of the potentially most serious is the effect of underwater light propagation, i.e., the scattering of the optical beam into a cone of steadily increasing angle. The basic premise of airborne laser hydrography is that the water depth can be determined by measuring the round-trip transit time for a short-duration light pulse which travels to the bottom and back to the surface along a fixed slanted path which makes a known angle from the vertical.
Displacement resolution of 10 μm achieved for typical 1-m objects
Authors: Giglio M. , Musazzi S. , Perini U.
Published: February 2020

We describe a high-resolution white-light speckle photographic technique for the study of in-plane displacements of large flat objects (linear dimension of the order of 1 m). The specklegrams are obtained with a 4 × 4-in. custom-made camera fitted with a high-performance lens and operating at a magnification ratio of 1:20. The object is covered with a retro-reflective paint containing catadioptric glass spheres of ~50 μm in diameter.