bluuebunny/crossref_metadata_2025 huggingface dataset:
Biological treatment and exercise as an alternative to typical rheumatoid arthritis therapy: pathophysiology and effects
Authors: Aghadi Artur , Brzuszkiewicz Kinga , Dybała Edyta , Cuber Iwona , Mazurek Magdalena , Białowąs Edyta , Piekarska Małgorzata , Kasperski Radosław
Published: February 2023

Introduction: Rheumatoid arthritis (RA) is a chronic autoimmune disease of unknown etiology that mainly affects the joints, but extra-articular symptoms may also occur. The global prevalence of RA is approximately 5 cases per 1,000 adults[1]. A better understanding of the pathophysiology of the disease in the treatment of RA has led to the development of more effective treatments. Current drugs include glucocorticoids (GCs) and synthetic and biological disease-modifying anti-rheumatic drugs (DMARDs). Apart from these, the most commonly used analgesics are non-steroidal anti-inflammatory drugs (NSAIDs). BLMPs work by targeting specific molecules involved in the inflammatory process, not just symptom relief.

Purpose: To review the currently available PubMed data on biologics and exercise for RA and their mechanisms in the context of disease pathophysiology and future prospects.

Brief description of the state of knowledge: BLMPs are a necessary alternative in patients who have not achieved the treatment goal for 6 months or have experienced side effects during treatment with conventional disease-modifying drugs. We also analyzed the effect of exercise on the course of RA.

Conclusions: The introduction of bDMARDs has opened a new era in the treatment of diseases such as RA. However, due to the difficult access to this form of therapy, side effects, contraindications to currently used drugs, and increasingly well-known mechanisms, there is also a need to constantly search for new solutions. A growing body of evidence in recent years suggests that regular physical activity has a positive effect on various aspects of RA, including disease-related outcomes, mental well-being, and cardiovascular health. Also in this non-pharmacological field, further research is needed to fully understand the mechanisms behind these effects.
Third molars: not so NICE? risk factors for distal caries in mandibular second molars
Authors: Treifi Amir , Cooper Jessica , Yates Julian
Published: February 2023

UK guidelines currently advise against the prophylactic removal of mandibular third molars. However, growing evidence shows that asymptomatic impacted mandibular third molars may contribute to the formation of distal caries in mandibular second molars. Patients should be made aware that these guidelines do not necessarily prevent the potential development of decay or loss of mandibular second molars. A retrospective review, over 6 months, analysed the incidence and evaluated the risk for developing caries on the distal aspect of mandibular second molars, in patients referred for assessment of impacted third molars. Distal caries in the mandibular second molar was present in 24.1% of cases. Of these patients, 9% demonstrated caries bilaterally. In those who developed distal caries in the mandibular second molar, 76% of adjacent third molars demonstrated mesio-angular impaction, 91% of third molars were partially erupted, and 95% of third molars were either touching or in close proximity to the ACJ of the second molar tooth. The prophylactic removal or coronectomy of mesio-angluar or horizontally impacted third molars that are partially erupted and closely related to the ACJ of mandibular second molars may result in improved long-term patient outcomes.

CPD/Clinical Relevance: The prophylactic removal or coronectomy of certain third molars may result in improved long-term patient outcomes.
Perioperative management of patients with anaemia: a new guideline
Authors: McNally Scarlett A
Published: February 2023

Anaemia is common before major surgery and increases complications. A new guideline aims to help with early diagnosis of the type and cause of anaemia and initiate effective treatment. The guideline includes clear education for all staff and patients about the biology of iron homeostasis and patient blood management.
Calidad de vida asociada con polifarmacia en personas con lesiones cutáneas crónicas
Authors: de Almeida Eliane Ferreira , Goulart Jéssica , Moraes Juliano Teixeira , Lanza Fernanda Moura , Cortez Daniel Nogueira
Published: February 2023

Objetivo:

Analizar la asociación entre el uso de polifarmacia y la calidad de vida de personas con lesiones cutáneas crónicas.

Método:

Estudio transversal con una muestra conformada por 146 personas afectadas por lesiones cutáneas crónicas, vinculadas con la atención primaria de salud. La recolección de datos se realizó entre julio de 2017 y febrero de 2018. La información se recopiló mediante un cuestionario sociodemográfico y el cuestionario Cardiff Wound Impact Schedule (CWIS).

Resultados:

Hubo predominio de hipertensión arterial sistémica en 86 personas (58,9%) y de diabetes mellitus en 50 (34,2%). La etiología de la lesión cutánea predominante fue vasculogénica (38,4%), y se identificó polifarmacia en el 46,7% de los pacientes. En el cuestionario CWIS, el dominio con el puntaje promedio más bajo fue el bienestar (promedio de 46,2±17,9). Hubo asociación estadísticamente significativa (p<0.05) entre polifarmacia y las siguientes variables: dominio de “síntomas físicos/vida diaria", dominio de “vida social” y “autosatisfacción con la calidad de vida".

Conclusión:

La polifarmacia está asociada con un detrimento en la calidad de vida de personas con lesiones cutáneas crónicas. Por lo tanto, los profesionales de la salud que trabajan en la atención primaria deberían considerar la terapia farmacológica en sus planes de atención, coordinar con asistencia médica y farmacéutica la elaboración de estrategias de monitoreo de los riesgos que involucran la polifarmacia, y evaluar sus impactos en la calidad de vida.

Conflicto de interés:

Ninguno.
How to Build an Industrial Vehicle
Authors: Scheffels Gerald
Published: February 2023

IN THE SECOND PART OF OUR HOW TO BUILD AN INDUSTRIAL VEHICLE SERIES WE LOOK AT HOW, ONCE IDEAS ARE DECIDED UPON, THE LATEST CUTTING-EDGE SOFTWARE AND TECHNIQUES CAN BE USED TO ENSURE THE ENGINEERING PROCESS IS ACCELERATED - EVEN AS DESIGNS BECOME MORE COMPLEX
Dirt Rider
Authors: Donlevy Michael
Published: February 2023

THE TA300 ARTICULATED HAULER FROM TEREX TRUCKS HAS JUST BEEN UPDATED WITH A WEALTH OF FRESH ENHANCEMENTS, INCLUDING A COMPLETELY NEW TRANSMISSION, TO ENABLE IT TO POWER THROUGH THE STICKIEST OF SITUATIONS, AHAD OF THE COMPETITION
Global Village: Get Ready for Bauma
Authors: Harry Rachelle
Published: February 2023

ON APRIL 8-14, THE CONSTRUCTION VEHICLE WORLD WILL DESCEND ON MUNICH FOR THE WORLD'S LARGEST CONSTRUCTION TRADE FAIR - BAUMA. THIS YEAR ORGANIZERS ARE CONFIDENTLY PREDICTING VISITOR NUMBERS WILL EXCEED 600,000 FOR THE FIRST TIME. BUT HOW CAN YOU POSSIBLY MAKE SENSE OF IT ALL? THE ANSWER LIES OVER THE NEXT 75 PAGES, WHICH WILL GUIDE YOU TO THE VERY BEST NEW VEHICLES AND COMPONENTS ON DISPLAY. SEE YOU IN GERMANY!

IN THE RUN-UP TO THE MAIN EVENT, EXHIBITION DIRECTOR MAREILE KÄSTNER EXPLAINS HOW THE CONSTRUCTION TRADE FAIR WILL HELP TO ADDRESS TOPICAL ISSUES SUCH AS DIGITIZATION AND THE SKILLS SHORTAGE - AND WHY ALL ATTENDEES SHOULD VISIT THE SELFIE TOWER!
Design Made Easy
Authors: Herrin Jeff , Clausen Morten
Published: February 2023

RAPID TECHNOLOGICAL DEVELOPMENTS IN THE OFF-HIGHWAY INDUSTRY MEAN MANUFACTURERS MUST INVEST IN ELECTRIC, CONNECTED OR AUTONOMOUS SOLUTIONS TO STAY AHEAD OF THE GAME
Intelligent Testing Tools
Authors: Lothigius Fredrik , Etzkorn Jutta
Published: February 2023

IN MOBILE HYDRAULICS IT IS VITAL FOR CYLINDERS, MOTORS, PUMPS, VALVES, HOSES, PIPES, SCREW CONNECTIONS AND MULTICOUPLINGS TO FUNCTION WITH ABSOLUTE RELIABILITY, RIGHT DOWN TO THE SEALS
Smooth Lifting and Lowering
Authors: Schneider Jürg
Published: February 2023

HOW CAN RAPID LIFTING AND LOWERING FUNCTIONS BE OPTIMALLY CONTROLLED IN ALL LOADING SYSTEMS? PROPORTIONAL THROTTLE AND FLOW CONTROL VALVES IN A WIDE RANGE OF SIZES AND EXECUTIONS ARE AN IDEAL SOLUTION
Excavator Hydraulics
Authors: Boote John
Published: February 2023

MANUFACTURERS ARE DRAWING ON MULTIPLE DECADES OF EXPERIENCE TO DEVELOP FUEL-EFFICIENT HYDRAULIC COMPONENTS SPECIFICALLY FOR EXCAVATORS, PREPARING THE VEHICLES FOR FUTURE TECHNOLOGICAL TRENDS
Software for Hydraulics
Authors: Brand Michael
Published: February 2023

DIGITAL CONTROLLERS ADJUST VARIABLE DISPLACEMENT PUMPS TO SUIT VARIOUS TASKS IN MOBILE WORKING MACHINES
Preparing for Autonomy
Authors: Locatelli Andreas
Published: February 2023

THE DEMAND FOR AUTONOMOUS OPERATIONS IN THE OFF-HIGHWAY INDUSTRY IS INCREASING. TO MEET THIS NEED, HIGH SAFETY STANDARDS MUST BE CONSIDERED AND IN-VEHICLE ARCHITECTURES NEED TO BE REDEVELOPED
A Console for Control
Authors: Habicht Nils
Published: February 2023

CONSOLES FOR OPERATORS USING MOBILE MACHINERY MUST BE VERSATILE AND EASY TO USE, AND DISPLAY WITH CLARITY
Drivetrain Optimization
Authors: Hakala Heikki
Published: February 2023

TO MANAGE CONTROLS AND ENERGY FLOW IN SYSTEMS MADE UP OF MULTIPLE SOURCES OF ENERGY, A COMPLEX CONTROL STRATEGY IS REQUIRED TO REALIZE THE FULL BENEFITS OF THE HYBRID POWERTRAIN
Inside the Comfort Zone
Authors: Medici Mauro
Published: February 2023

A GROUP OF EUROPEAN CAB MAKERS HAVE COMBINED THEIR EXPERTISE AND JOINED FORCES TO FACE THE MARKET WITH A BRAND-NEW APPROACH
One-Stop HVAC Shop
Authors: Göpel Eric
Published: February 2023

OPTIMAL THERMAL MANAGEMENT IN CONSTRUCTION - FOR THE MACHINERY ITSELF, AS WELL AS THE OPERATOR CAB - IS CRUCIAL FOR WORK TO BE CARRIED OUT DURING ALL WEATHER CONDITIONS
Cabin Fever
Authors: Wordsworth Saul
Published: February 2023

A KEY USP IN TODAY'S OFF-HIGHWAY VEHICLES IS CAB ERGONOMICS, WHICH IS WHY IT IS A PRIMARY FOCUS FOR INNOVATION. iVT MEETS THE OEM DESIGNERS AND TIER 1 SUPPLIERS WHO ARE HELPING TO DEFINE THE OPERATOR AREAS OF THE FUTURE
Above and Beyond
Authors: Allen James
Published: February 2023

MANY IMPORTANT UPGRADES HAVE BEEN MADE DURING DOOSAN'S REFRESH OF ITS DA30 ARTICULATED HAULER, BUT IT'S STILL UNDENIABLY ONE OF THE TOUGHEST CONTENDERS IN ITS CLASS
Compact Stage V Power
Authors: Gritsch Stephan
Published: February 2023

UPGRADING SMALL MACHINES TO STAGE V CAN BE A CHALLENGE, WHICH IS WHY OEMs ARE LOOKING TO COMPACT SOLUTIONS THAT WON'T REQUIRE EXTENSTIVE VEHICLE REDESIGNS
Up in the Cold
Authors: Colucci Frank
Published: February 2023

The flight test campaign for the Bell 525 Relentless helicopter included collecting certification data in the cold Candian Winter
Approved to Carry
Authors: Hughes David
Published: February 2023

With Clead Approval Requirements and Business Cases, the Rollout of Fully Autonomous Cargo Aircraft has Begun a Already
Anders Forslund, Founder and CEO of Heart Aerospace
Authors: Sampson Ben
Published: February 2023

The Ceo of Swedish Startup Heart Aerospace Discusses the Advantages of their Measured Approach to Testing and Certifying its All-Electric Regional Aircraft
Redefining Fatigue
Authors: Pittaway Nigel
Published: February 2023

A 14 year long full-scale fatigue test has proved the longevity of one of the world's most popular trainer jets
Measurements for Additive Manufacturing
Authors: James Anthony
Published: February 2023

The use of 3D printing continues to grow in aerospace, but the proper inspection of the parts it produces requires a significant departure from traditional metrology methods
UP for Discussion
Authors: Beck Chris
Published: February 2023

A German-style collaborative approach between manufacturers, government and the public could be the key to both driving the Fourth Industrial Revolution and combatting the skills shortage facing manufacturing, Tim Hulbert, UK vice-president of Air Products, tells Manufacturing Management
Pensioned Off?
Authors: Bernstein Adam
Published: February 2023

The government’s pension auto-enrolment scheme has brought saving for the future into the minds of employers and employees alike. But are companies, including manufacturers, risking fines by not complying with the policy?
Cost Control
Authors: Roper Jack
Published: February 2023

Overhead line electrification is often considered the optimal solution for decarbonizing intensively used rail lines, but cost remains a key challenge. Network operators from around the world reveal the cost-cutting measures they are implementing to accelerate OLE roll out
Put to the Testing Test
Authors: Norman Helen
Published: February 2023

The UK’s rolling stock and infrastructure testing landscape is be ing given a huge boost thanks to significant investments in a new proving ground for accelerating decarbonization and upgraded test rigs for pantograph and energy harvesting system research
Source Material
Authors: Triviño Angel Castillejo
Published: February 2023

Aismalibar provides an overview of its latest thermal interface material technology used in power electronics for railway applications
Sustainable Reprofiling
Authors: van Ackeren Janine
Published: February 2023

Hexagon Purus reveals the main considerations of installing a fuel storage system on the world’s first hydrogen-powered and zero emission rail reprofiling locomotive
The Power of Trains to Fight Climate Change in the US
Authors: Harnish Rick
Published: February 2023

Relatively few Americans have an of idea how far train technology has come in recent years. The amenities and comfort of state-of the-art, zero-emissions electric trains must be experienced to be believed. And the technology just keeps getting better.
Rainfall-Induced Optical Phase Fluctuations in the Atmosphere
Authors: Yura H. T.
Published: February 2023

The effective use of coherent optical systems in the field, such as lasers, depends strongly on maintaining a relatively high degree of lateral phase coherence over mutual separations that correspond to aperture sizes of practical concern. It is anticipated that such systems, to be of any general utility, will operate under a wide variety of environmental conditions such as clear-air turbulence, rain, fog, snow, etc. In this paper we investigate, theoretically, the effect of rain-induced optical phase fluctuations of an initially coherent wave propagating through the lower atmosphere. In this regard it should be mentioned that clear-air turbulence-induced phase fluctuations have been thoroughly investigated and are well documented in the literature(1). Although rain-induced irradiance fluctuation has been considered previously,(2) this paper, to the best of our knowledge, is the first treatment of rain-induced phase fluctuations and their associated effects on coherent optical systems.
Determination of Rain Rate and Turbulence by Phase Fluctuation Measurement with a Dual Channel CO2-Laser-System
Authors: Barthel K.G. , Büchtemann W.
Published: February 2023

We have implemented a CO2-laser heterodyne system with which very efficiently phase difference fluctuations and power spectra caused by atmospheric propagation of the radiation can be determined. Examples, demonstrating the capability of the system to measure path averaged crosswind velocity and rain rate, are presented.
Calibration of Lidar Aerosol Backscatter Data Using Hard Target Reflectance Measurements
Authors: Kavaya Michael J. , Menzies Robert T. , Haner David A. , Oppenheim Uri P.
Published: February 2023

A coherent laser radar has been constructed, using an injection locked TEA-CO2 laser transmitter which is grating tunable from 9-11 μm, to measure tropospheric aerosol backscatter coefficients as a function of altitude and wavelength. A standard hard target is desired to aid in the calibration of the responsivity of the coherent lidar system and to allow quantitative comparison of our backscatter data with data taken by others. An ideal target would be easy to fabricate, reproducible, durable, and have a well-known bidirectional reflectance-distribution function (BRDF)1,2 at all wavelengths in the spectral region of interest.
Experimental Verification of a Diffraction Limited Lidar
Authors: Lading Lars , Jensen Arne Skov
Published: February 2023

Traditional visible lidars are far from diffraction limited. Transmitter and receiver are not exactly matched. A diffraction limited system provides for a lower background and a return signal better suited for analysis by high resolution interferometers or even heterodyning. A diffraction limited system will in general have a range weighting different from the simple 1/z2 -dependence. Strong focusing may be encountered. They are also considered to be much more susceptible to optical refractive turbulence.
Relationships between Satellite Detected Radiance and Simultaneously Measured Marine Aerosols and State Variables
Authors: Jensen D. R. , Durkee P. A. , Hindman E. E.
Published: February 2023

Regions of brightness variations are often observed in the visible and near-infrared satellite images of cloud-free, coastal regions. Fett and Isaacs (1979) hypothesized that these brightness variations result from changes in low-level aerosol particles distributions due to relative humidity fluctuations. This hypothesis was tested theoretically by Isaacs (1980) and was found to be plausible. Hindman et al, (1983) found that satellite detected radiance and simultaneously measured particles concentrations show an apparent positive relationship, but that more data are needed to make any firm conclusion.
Real-Time Processing and Display of Coherent Lidar Returns
Authors: Hardesty R. M. , Lee R. W. , Davis D. L.
Published: February 2023

Prior to 1983, 95% of signal processing for the NOAA coherent lidar system was performed off-line. This limited real-time processing and display performance hampered the utility of the lidar in experiments such as JAWS1 (Joint Airport Weather Study) where the inability to detect and track interesting meteorological phenomena severely limited the quantity of useful data-recorded. During JAWS, we were able to monitor radial velocities in only one range gate at any given time, thus often missing the presence of an interesting event occurring at another range.
Influence of Clouds and Fog on CW-LDA-Systems
Authors: Werner Ch. , Köpp F. , Schwiesow R.L.
Published: February 2023

To measure the wind velocity with a cw-laser Doppler anemometer (LDA) in a defined volume, it is necessary to focus the cw-laser radiation (Köpp, 1982). The backscattered light from the range R comes from a volume of the length △L with where D is the diameter of the telescope (in our case 30 cm) and λ is the wavelength.
The NH2D Stark Effect Frequency Stabilization of CO2 Laser
Authors: Mingjia Pi , Yongjiang Dai , Zaoyan Liu , Jingda Nan , Yuzen Jiang
Published: February 2023

The transfer function of the first-order linear control loop are worked out and studied, and a type of second-order loop is discussed. Long-term frequency stability of better than ±5KHZ is obtained.
Aperture Effects in Waveguide Lasers
Authors: DiMarzio Charles A. , McVicker David B.
Published: February 2023

Recently, CO2 waveguide lasers with intra-cavity modulators have been used as sources for laser radars. The losses in these lasers are analyzed and compared to experiment.
Modeling Studies of Pt/SnO2 Catalysed CO-O2 Recombination For Closed-Cycle CO2 Lasers
Authors: Sidney Barry D. , Schryer David R. , Brown Kenneth G. , van Norman John
Published: February 2023

Pulsed CO2 lasers have several potential remote sensing applications, both military and non-military, which require long-life operation with high conversion-efficiency and good power-stability.
Homodyne Detection for Optical Space Communications
Authors: Hacker G.
Published: February 2023

Optical communication systems offer significant advantages over conventional microwave communications. They have the potential to provide high rate data links between satellites. Moving on to the optical frequency regime provides increased antenna gain with small congestion occuring in microwave communications. These properties and the high privacy due to the high directivity and small beam width make optical communications systems an ideal candidate for future intersatellite/interorbit data links.
Development and Application of an Injection Locked, Pulsed CO2 Doppler Lidar for Atmospheric Remote Sensing
Authors: Hardesty R. M. , Cupp R. E. , Lawrence T. R.
Published: February 2023

During the summer of 1985, the Wave Propagation Laboratory of NOAA upgraded its pulsed CO2 Doppler lidar with a new transceiver. Previously, the system had operated with a hybrid TEA transmitter, producing approximately 100 mJ of energy per pulse at a 10 Hz pulse repetition frequency (prf). The upgraded transceiver, built by Spectra Technologies, Incorporated, of Bellevue, Washington, uses an injection-locked, unstable resonator configuration to produce frequency-stable pulses with 2 J of energy per pulse; maximum prf of the injection-locked system is 50 Hz. The larger pulse energy and higher pulse repetition frequency make the new lidar considerably more valuable for investigations of transient atmospheric phenomena and tropospheric backscatter climatology.
Airborne Coherent CO2 Lidar for Measurements of Aerosol Backscatter Profiles
Authors: Menzies Robert T.
Published: February 2023

An airborne range-gated CO2 lidar is being developed at JPL to measure vertical profiles of aerosol backscatter throughout the vertical extent of the troposphere and lower stratosphere, with emphasis on coverage of a wide range of latitudes, including the equatorial region and portions of the southern hemisphere. The acquisition and interpretation of aerosol backscatter data over large geographical regions, using a direct measurement technique as exemplified by the range-gated CO2 lidar approach, is key to the evaluation of coherent Doppler lidar techniques for the measurement of global wind fields from an Earth-orbiting platform. The lidar studies, when combined with studies of aerosol sampler data both from the aircraft platform and from various ground-based stations in the Pacific Ocean basin, will elucidate the effects of transport and various aerosol sinks on global-scale aerosol distributions in the troposphere. These studies comprise a major part of the NASA GLOBE (GLobal Backscatter Experiment) program, which is being coordinated by the NASA Marshall Space Flight Center.
THE GLObal Backscatter Experiment (GLOBE) Program
Authors: Bowdle David A. , Fitzjarrald Daniel E.
Published: February 2023

NASA has recently initiated a major program, the GLObal Backscatter Experiment (GLOBE), to measure atmospheric aerosol backscatter and related aerosol physical, chemical, and optical properties. The comprehensive aerosol data base from this effort will be used to develop a global-scale model of the typical magnitudes and the spatial / temporal variability of aerosol backscatter. The model will be used in design and simulation studies for NASA’s (National Aeronautics and Space Administration) Doppler Lidar Atmospheric Wind Sounder (LAWS) (Baker and Curran, 1985), which is planned for deployment to low earth orbit in the mid 1990’s.
Mauna Loa Aerosol Backscatter Intercomparison Experiment (MABIE)
Authors: Bowdle David A. , Jones William D. , Clarke Antony D. , Johnson Stanley A. , Fitzjarrald Daniel E.
Published: February 2023

Measurements of aerosol backscatter coefficients at 10.6 micrometers wavelength have been obtained with a focused continuous-wave (CW) CO2 Doppler lidar (Jones et al, 1984) in August, 1986, at the Mauna Loa Observatory (MLO) on the island of Hawaii. Concurrent measurements were obtained of related aerosol physicochemical properties. To the authors’ knowledge, these CO2 backscatter measurements are the first ever obtained in free tropospheric airmasses over the remote Pacific Ocean. Previous measurements of this kind were restricted to Pacific airmasses advected over CO2 lidar test sites on or near large land masses (Menzies et al, 1984).
Kinetics Review of CO2 Room Temperature Catalysts
Authors: Lewis P. , Kurzius Shelby C.
Published: February 2023

A substantial body of data is becoming available on "room" temperature catalysts for CO oxidation in CO2 lasers. This data is sometimes confusing and often presented in a form that does not allow the laser system designer to make a confident evaluation of the catalyst for his purpose. It may further be that catalyst cost is not the primary consideration for selection so that performance evaluation becomes increasingly important.
A Compact, Injection-Seeded, Heterodyne Lidar: Lessons Learned From Airborne Tests
Authors: Schwiesow R. L. , Spowart M. P.
Published: February 2023

The NCAR airborne infrared lidar system (NAILS) is being developed over a number of years with the eventual goal of Doppler wind measurements for applications to research in atmospheric science. The system is based on a pulsed CO2 laser using a transverse-excitation, atmospheric-pressure (TEA) discharge. Research results from NAILS in a direct-detection mode have recently appeared (Schwiesow, et al., 1990b), and a number of applications for the heterodyne version have been discussed in a meteorological context (Schwiesow et al., 1991).
Doppler Detection at High Instabilities of Laser Sources
Authors: Stoyanov D. V. , Bratanov B. M. , Angelova M. D.
Published: February 2023

The Doppler detection schemes, effective at high frequency instabilities of laser sources are of great interest for lidar performance. The stability of ≈ 10−9 is required to realize ≈ ± 1 m/s accuracy of wind speed [1,2]. Doppler detection schemes on the intermediate frequency opera ting at stabilities of order of 10−7 ÷ 10−6 are described here, based on the so-called tracking heterodyne [3,4] and the proper lidar synchronization.
A Design Study for the Laser Atmospheric Wind Sounder (LAWS) Transmitter
Authors: Ghoshroy Subrata , Chou Hsian Pei , Kurzius Shelby C.
Published: February 2023

A conceptual design study of the laser transmitter was completed during Phase A of the NASA's LAWS instrument development program. The proposed LAWS instrument is a space-based doppler lidar wind profiler consisting of a pulsed, frequency-stable laser as its transmitter, which is the subject of this paper. The telescope, heterodyne detection system and signal processor designs will be reported in another paper.(1) While both solid-state and CO2 lasers were considered as potential candidates for the LAWS instrument, it became clear early on that CO2 lasers had definite advantages over the solid-state at the present time. Although, the solid-state technology is rapidly advancing, it does not yet have the maturity enjoyed by the CO2 technology.(2) Furthermore, the CO2 wavelength is clearly favored from eye safety consideration. Therefore, our design study was performed primarily for a pulsed CO2 laser.
Compact High Energy Nd: YAG Coherent Laser Radar Transceiver
Authors: Hale C.P. , Henderson S.W. , Magee J.R. , Vetorino S.R.
Published: February 2023

Numerous coherent laser radar (CLR) applications exist in defense and commercial arenas for compact, high energy transmitter/receiver systems. The use of solid-state laser sources in the near- and mid-IR are of particular interest, as these lasers and laser amplifiers offer near-term promise of very efficient, lightweight CLR transmitters at relatively low cost. Building on previous work with Nd: YAG CLR technology at 1.06 μm wavelength,1,2 we report here on the development of a engineered Nd: YAG transceiver having considerable operating flexibility, arbitrary optical pulse-forming capability, high pulse energy, and > 20 Hz pulse repetition rate.
ESA Progress in Spaceborne Doppler Wind Lidar Activities
Authors: Marini A. , Culoma A.
Published: February 2023

Space-borne global wind observation is considered a high-priority mission for the next two decades, in view of the unique benefits that operational meteorology and climate research would receive. A satellite-borne Doppler wind lidar has been recognised a potential corner-stone instrument of future wind-monitoring systems, due to its capability of measuring wind profiles on global scale with high accuracy.
Temporal simulation for space borne coherent Doppler lidar
Authors: Salamitou Philippe , Flamant Pierre H.
Published: February 2023

The purpose of the simulation model, LITSAT, is to assess the performance of a space coherent Doppler wind lidar for atmospheric sounding. It has been developed to help design instrumental concepts for the ALADIN pre-Phase A study.
Performance of a CO2 Laser for Space Windlidar Applications
Authors: Willetts D V , Harris M R , Armandillo E , Norrie C , Schwarzenberger P M , Wallace S , Schäper W , Gollor M , Galletti E , Stucchi E
Published: February 2023

The space-based Doppler windlidar concept is now well established. An orbiting coherent laser illuminates the atmosphere and backscattered radiation is coherently detected on the satellite. The Doppler shift and thus wind velocity are extracted, and the whole earth can be sampled with a horizontal resolution of order a few hundred kilometres and a daily update rate. The transmitter laser capability has been perceived to be a critical aspect of overall system performance, and as part of its Doppler windlidar programme, the European Space Agency is currently funding an advanced research programme on CO2 laser source development.
An Overview of the Lite Flight on Discovery and Its Impact On Future Lidar Missions
Authors: Winker D. M.
Published: February 2023

LITE is a three-wavelength backscatter lidar developed by NASA Langley Research Center which was flown on the STS-64 mission in September 1994. The instrument was operated between the latitudes of 57°N and 57°S during 10 days of the mission. The instrument was designed to study a wide range of cloud and aerosol phenomena and a comprehensive program of scientific investigations was conducted during the mission. The instrument has sufficient sensitivity to detect subvisible cirrus and boundary layer aerosols on a single-shot basis. Signal averaging provides the capability of observing the stratospheric aerosol layer and density profiles to an altitude of 40 km.
Coherent vs Incoherent Space-Based Doppler Lidar Sampling Patterns: Accuracy And Representativeness
Authors: Emmitt G.D.
Published: February 2023

Space-based observations of the tropospheric winds are critical to improving atmospheric forecast and diagnostic modeling. Doppler lidars have been proposed, for some time, to meet the technological challenge of direct and remote measurement of air motion. Being direct, the lidar observations offer the potential for more accurate measurements than those inferred from cloud motion or sea surface roughness. However, accuracy is only one component in the more important issue of representativeness. Sampling density, shot pattern and lateral coverage have merits similar to that of accuracy when addressing the impact of observations on global atmospheric modeling. This presentation will deal with the issue of representativeness or maximum variance reduction as they relate to the dueling concepts of coherent and incoherent Doppler lidars.
Lidar Measurements at Heathrow and Structure in the B747 Vortex
Authors: Vaughan J.M. , Brown D. , Constant G. , Eacock J. , Foord R.
Published: February 2023

The wake vortices of nearly 2000 aircraft landing at Heathrow have been recorded with a CW CO2 Lidar. Very characteristic differences are apparent, including clear evidence of structure within the B747 vortex.
Measurement of Small Motions using a 2-micron Coherent Laser Radar
Authors: Henderson Sammy W. , Thomson J. Alex L. , Wilson Geoffrey A. , Vetorino Steven R. , Hannon Stephen M. , Hale Charley P.
Published: February 2023

Coherent Technologies, Inc. has developed, under ARPA and Wright Laboratory funding, a lidar sensor capable of remotely detecting small motions (e.g. vibrations) of solid objects. The sensor is a coherent laser radar using a solid-state laser operating at a wavelength of 2 μm. Coherent lidar sensors capable of long-range remote vibration measurement utilizing CO2 lasers operating at 10.6 μm have been previously reported (e.g., see references 1 and 2). Operation at the 2-μm wavelength results in improved atmospheric transmission and better spatial and velocity resolution. The 2-μm lidar instrument has demonstrated the ability to sense target velocities as small as a few hundred μm/s in measurement times of 10-100 μs. The measurement precision demonstrated agrees well with predictions of theoretical analysis and Monte Carlo simulations of the measurement process. Measurements of the motion signatures of targets located at 0.1 ~0.5 km range have been demonstrated.
Development of a dual-wavelength CO2 Mini-MOPA Doppler Lidar
Authors: Brewer W. Alan , Hardesty R. Michael
Published: February 2023

During 1992, we used a compact, radio-frequency (rf) excited, CO2 coherent lidar to measure winds in the marine boundary layer. This system employed a Q-switched master oscillator, frequency offset local oscillator, and power amplifier unit to provide 1-3 mJ of energies at pulse rates of 200 Hz. The lidar is currently being modified to provide measurements at two wavelengths, which will enable simultaneous Doppler wind observations and differential absorption lidar (DIAL) species concentration measurements in the lower 3-5 km of the atmosphere. It is hoped that the instrument will be able to provide concentration and vertical flux profiles of water vapor and ozone, as well as discriminate between cloud ice and water particles, to support climate and global change related research in the lower troposphere.
A New Te-CO2 Laser for Coherent Lidar and Wind Applications
Authors: Delville P. , Loth C. , Bruneau D. , Flamant P.H. , Le Floch Th. , Farcy J-C.
Published: February 2023

A compact single mode TE-CO2 laser has been developped by Société Anonyme de Télécommunications (SAT) for wind measurement applications for the French-German WIND (Wind INfrared Doppler Lidar) program (1). The laser transmitter is a critical component considering the performance. The key parameters are the frequency stability (jitter) from shot to shot, the intra frequency sweeping (chirp), the pulse length and shape, and the output energy. Regarding an airborne application in a medium size aircraft, the other relevant characteristics are the wall plug efficiency, and overall size and weight. All these parameters are crucial for reliable operation. We report on the design and tests conducted on a laser breadboard prior the fabrication of the flight model. In addition, the new laser has been implemented in the LMD ground-based coherent lidar for atmospheric measurements and used since several months.
Diode-pumped, 6-mJ, Repetitively Q-switched Tm, Ho:YLF Laser for Clear Air Turbulence Detection
Authors: Finch Andrew , Flint John H.
Published: February 2023

It has long been recognized that the detection and avoidance of Clear Air Turbulence can benefit both military and civilian airfleet operations in terms of passenger safety and comfort, as well as economic and mission performance. Among a variety of lidar systems under development, we are currently constructing a 2 μm Q-switched Tm,Ho:YLF laser transmitter/coherent receiver system specifically designed for CAT detection. Within this program, goal detection ranges are up to 20 km with real-time data update rates. This leads to a performance specification for the 2-μm laser system of 5 mJ at a repetition rate of 200 Hz with a 200 ns pulse duration. Towards this goal, we have recently demonstrated efficient operation of a Tm,Ho:YLF laser pumped by a 20-W fiber coupled CW laser diode array. We have obtained ~6 mJ of Q-switched pulse energy at repetition rates of 50 - 200 Hz and over 3 mJ at a 1 kHz repetition rate. In CW operation we have obtained over 4.5 W of power. In all cases the lasing mode was TEM00.
Micro-external-cavity Semiconductor Laser on a Silicon Chip - a Miniaturized, Continuously Tunable, Narrow-linewidth Laser for Coherent Lidar
Authors: Solgaard O. , Tien N. , Daneman M. , Kiang M. , Muller R.S. , Lau K.Y.
Published: February 2023

Successful large-scale introduction of coherent-lidar/remote-sensing techniques in environmental monitoring is hindered currently by the relatively high cost of continuously tunable, narrow-linewidth laser sources, as well as their relative bulkiness that preclude their installations in confined spaces. While semiconductor lasers are currently massed-produced at low cost, the requirements of narrow-linewidth and continuously tunable necessitates coupling the laser diode to an external cavity grating which makes its cost very high. In this paper, we describe a new technology that has evolved in the past year, that uses silicon micromachining technology to implement a miniaturized, lost cost, continuously tunble, highly coherent, micro External- Cavity semiconductor Laser (micro-ECL). The entire optical system is built on a silicon chip measuring less than 0.3cm square, and on-chip micromotors are used to drive the grating reflector for continuous wavelength tuning. The semiconductor laser can also be made to emit very short, wavelength tunable pulses by simply electrically driving the laser diode. A schematic of the micro-ECL is shown in Fig. 1.
Heterodyne Detection and Multiple Scattering in Cirrus Clouds
Authors: Nicolas F. , Flamant P. H. , Dabas A.
Published: February 2023

Cirrus gives strong returns to provide with relevant informations on atmospheric dynamics in the upper troposphere. However, multiple scattering plays a major role in dense media like clouds, which could be detrimental to the signal analysis. Thus, we study the importance of multiple scattering on wind remote sensing by a coherent lidar for the case of cirrus made of large particles compared to the wavelength.
Filtering of Pulse-Spike-Induced Uncertainty In Deconvolved Doppler-Lidar Power Profiles
Authors: Stoyanov D.V. , Gurdev L.L. , Dreischuh T.N.
Published: February 2023

The deconvolution of lidar profiles is an effective software way to improve the lidar resolution and to extract small-scale aerosol inhomogeneities, especially in coherent CO2 (Doppler and DIAL) lidars, where long laser pulses are emitted as a rule by TE (TEA) CO2 laser transmitters (see e.g.[1]). Different deconvolution techniques, based on the Fourier transformation or Volterra integral equation or a recurrence relation have been developed in [2,3]. As shown in [4], the uncertainty in the measurement of the laser pulse shape (e.g. a spike cut) causes a shift up or down as a whole of the restored lidar profile (with respect to the true one) and distortions in the spectrum of the retrieved inhomogeneities. As a rule the spike duration does not exceed several sampling intervals Δt. On the other hand, the increase of the sampling rate to reduce the uncertainty causes hardware problems such as higher data rate, lower dynamic range etc.
Advanced Lithography for Nanofabrication
Authors: Eres Gyula , Hui Frank Y. C.
Published: February 2023

Nanostructures are defined to be ultrasmall structures and devices with dimensions less than or equal to 100 nm. Conventional methods for making thin film structures involve exposure of a thin layer of a polymer resist on a suitable substrate to define a pattern, which is than developed and used to fabricate the structures either by deposition, or by etching [1]. The feature sizes of the structures depend both on the resolution of the resist and the imaging method used to expose the resist [1,2]. The materials quality of nanostrustures is also an important factor. In many cases the nanostructures must be crystallographically perfect. Resistless methods of patterning, followed by epitaxial growth could significantly simplify nanofabrication by eliminating a number of processing steps associated with the application, exposure, development, and removal of the resist. The advantage of epitaxial growth is that unlike etching, it is less prone to produce damage in the regions adjacent to the structures. The molecular size effect with polymer based resists such as PMMA is believed to be a significant factor in limiting the resolution (“grain size”) in electron beam lithography (EBL) to 10 nm. Surface adsorption layers such as the hydride layer on the Si surface are characterized by relatively strong chemical bonding which produces a highly uniform coverage that terminates at a single monolayer. Because of these properties surface adsorption layers are attractive candidates as ultrathin, ultrahigh resolution resists for electron beam patterning.
The Nanofabrication Challenges in Realizing Quantum Effect Integrated Circuits
Authors: Broekaert T. P. E. , Randall J. N. , Beam E. A. , Frazier G. A. , Jovanovic D. , Seabaugh A. C. , Smith B. D.
Published: February 2023

Lateral heterostructure resonant tunneling transistors have the potential to become the fundamental device technology for ultra-scaled integrated circuits. Manufacturing these circuits will require near atomic scale precision.
Formation and electronic properties of sidewall quantum wires on patterned GaAs (311)A substrates.
Authors: Nötzel Richard , Ramsteiner Manfred , Däweritz Lutz , Ploog K.H.
Published: February 2023

The natural formation of nanometer-scale structures on high-index semiconductor surfaces during molecular beam epitaxy (MBE) [1] and metalorganic vapor phase epitaxy (MOVPE) [2] has opened a new pathway for the realization of quantum-wire and dot arrays. Even higher flexibility in the formation of nanostructures on high-index semiconductor surfaces can be realized by growth on patterned substrates. Patterning provides an additional degree of freedom for the control of the size and, most important, allows the precise placing of the nanostructures desired for applications in devices.
Influence of Feature Size Scaling on Chemical Vapor Deposition Chemistry
Authors: Houle F. A. , Ure J. , Clemes T. , Bond J. , Sharma P. , Coughlan M. , Singmaster K. A.
Published: February 2023

Chemical vapor deposition is uniquely suited for depositing metal films with characteristic dimensions ranging from nanometers to meters. The general utility of the method has been limited by the difficulty in controlling film purity for many metals, however, largely because of the complexities of gas-surface interactions as the films grow. There have been a number of studies addressing the surface chemistry of metal CVD for the aluminum alkyls, Cu(I) and Cu(II) complexes, Cr, Mo, W, Ni and Fe carbonyls and WF6.1 Most of this work has focussed on monolayer-level chemistry rather than deposition under steady-state gas flow at typical CVD pressures, so knowledge of factors affecting surface reactions leading to decomposition is still somewhat limited. In particular, the relationship between surface reactions and gas transport is essentially unexplored although it is a critical aspect of scaling of the chemistry with feature dimensions. This issue has received some attention in modelling of direct write deposition rates,2 although reaction mechanisms were not considered.
Theory of Single Slow Interface Traps in Submicron Metal-Oxide-Electron Field Effect Transistors (MOSFETs) and Single-Electron Spectroscopy of the Traps.
Authors: Fouks B.I.
Published: February 2023

The study of small semiconductor devices has made large contribution to solving the low-frequency 1/f noise problem. Experiments (see review [1]) have shown that the less size of device, the easier to observe that the 1/f current noise consists of the unit acts, which are often called random telegraph signals (RTSs) because of their shape. An RTS represents the jumps of a currents between two fixed levels, the duration of the jumps is instantaneous in practice in comparison to the duration of both states of the current, so the RTS is seen as sequence of the current up and down steps of the same value between high and low current states. The times between two neighboring steps are distributed at random with the mean times of high and low current states being very long. The less the size of the device, the less the number of RTSs observed simultaneously and the higher the relative contribution of each RTS to the total current. In submicron devices under certain conditions it is possible to study a single RTS [2]. RTS is caused by capture and emission of electrons (or holes) by a slow electron trap. Thus the study of an RTS in a small-size device permits to investigate the properties of a single slow trap existing in it. The effect of the external parameters, such as temperature, voltage etc. on RTS is generally much more pronounced than that of the 1/f noise consisting of many RTSs. This is the reason why the study of RTSs in submicron devices has given a new valuable information.
Pseudopotential Theory of Semiconductor Quantum Dots, Wires and Films
Authors: Zunger Alex
Published: February 2023

The electronic structure of nanostructures has been almost universally addressed by the “standard model” of effective-mass k·p envelope function approach. While eminently successful for quantum wells, this model breaks down for small structures, in particular, for small dots and wires[l]. Until recently, it was impractical to test the “standard model” against more general approaches that allow many-band (Γ-X-L) coupling. However, it is now possible, due to special tricks[2], to apply the all-band pseudopotential method to 103 - 104 atom nanostructures. This shows (i) how the “standard model” fails, for thin superlattices, [3], (ii) how size effect lead to a reduction in dielectric constants[3] and to band gaps that differ from what is expected in effective-mass theory, (iii) the emergence of a “zero-confinement state” in 2D films [4], (iv) that small dots of III-V materials have an indirect gap that converts to direct above a critical size[5], (v) how the spectra of CdSe dots evolve from the bulk[6] and (vi) how the spectra of dots of Si, GaAs, InP and CdSe compare with experiment, and (vii) how the use of pseudopotential wavefunctions leads to very different electron-hole coulomb and exchange energies relative to the “standard model”.
Electron Interference Fringes on a Pb Quantum Wedge
Authors: Altfeder I. B. , Chen D. M. , Matveev K. A.
Published: February 2023

Optical Fizeau fringes appear when a monochromatic light illuminates the surface of a thin optically transparent wedge. As the wavelength of the Fermi electrons in a metal is by a factor of 1000 smaller then the wavelength of light, one could expect to observe the similar phenomenon of electron interference fringes on a nanometer thickness metal wedge. The perfect tool to detect the electron interference pattern is a scanning tunneling microscope (STM), as it can probe the local density of states (LDOS), and test the interference conditions for the Fermi electrons. Indeed, the STM has been used successfully to reveal different surface interference phenomena (1-4).
Fabrication and Luminescence of Large Si Nanocrystals
Authors: Tsybeskov L. , Moore K. L. , Duttagupta S. P. , Hirschman K. D. , Hall D. G. , Fauchet P. M.
Published: February 2023

The photoluminescence (PL) in crystalline silicon (c-Si) has been investigated during the last decades. Recent interest has focused on the visible PL that is observed in Si nanoclusters and in porous Si (PSi), the infrared PL in silicon-germanium superlattices, and the subgap PL due to impurities in c-Si [1]. Band edge PL in bulk Si is inefficient and usually observed only at low temperatures because c-Si has an indirect bandgap. The electroluminescence (EL) is as inefficient as the photoluminescence (PL) and, in addition, the EL is quenched by an electric field E ≥ 104 V/cm due to field-induced dissociation of the exciton. In this work we report a significant increase of the Si band edge photoluminescence and electroluminescence and its unexpectedly weak temperature dependence in large Si nanocrystals produced by the recrystallization of oxidized porous Si.
Raytracing Models for Diffractive Optical Elements
Authors: Clark Peter P. , Londoño Carmiña
Published: February 2023

Optical designers currently have several ways to model surface relief diffractive optical elements (DOE's) on the computer. We are aware of three distinct techniques: the phase model1,2, the Sweatt model3 and the Southwell model4. We will compare them for accuracy, applicability and ease of use. These models must perform two functions: a) Accurately simulate the performance of the DOE. b) Be translatable into information that will allow the physical part to be produced.