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Sub-50 fs pulses at 2050 nm from a picosecond Ho:YLF laser using a two-stage Kagome-fiber-based compressor

Photonics Research 2022年第3期10卷 637-645页

作者： krishna murari Giovanni Cirmi Hüseyin Cankaya Gregory J.Stein Benoit Debord Frederic Gerome Felix Ritzkosky Fetah Benabid Oliver Muecke Franz X.Kärtner Center for Free Electron Laser Science CFEL Deutsches Elektronen-Synchrotron DESY22607 HamburgGermany Max-Planck Institute for Structure and Dynamics of Matter(MPSD) 22761 HamburgGermany ELI-ALPS ELI-HU Non-Profit Ltd.Szeged H-6728Hungary The Hamburg Center for Ultrafast Imaging&Department of Physics University of Hamburg22761 HamburgGermany GPPMM Group XLIM Research InstituteUMR 7252 CNRSUniversity of LimogesLimogesFrance show less

The high-energy few-cycle mid-infrared laser pulse beyond 2μm is of immense importance for attosecond science and strong-field ***,the limited gain bandwidth of laser crystals such as Ho:YLF and Ho:YAG allows the generation of picosecond(ps)long pulses and,hence,makes it challenging to generate few-cycle pulse at 2μm without utilizing an optical parametric chirped-pulse amplifier(OPCPA).Moreover,the exclusive use of the near-infrared wavelength has limited the generation of wavelengths beyond 4μm(OPCPA).Furthermore,high harmonic generation(HHG)conversion efficiency reduces dramatically when driven by a long-wavelength *** schemes such as multi-color HHG have been proposed to enhance the harmonic ***,it is highly desirable to generate few-cycle to femtosecond pulses from a 2μm laser for driving these ***,we utilize two-stage nonlinear spectral broadening and pulse compression based on the Kagome-type hollow-core photonic crystal fiber(HC-PCF)to compress few-ps pulses to sub-50 fs from a Ho:YLF amplifier at 2μm at 1 kHz repetition *** demonstrate both experimentally and numerically the compression of 3.3 ps at 140μJ pulses to 48 fs at 11μJ with focal intensity reaching 10^(13)W/cm^(***,this system can be used for driving HHG in solids at 2μ*** the first stage,the pulses are spectrally broadened in Kagome fiber and compressed in a silicon-based prism compressor to 285 fs at a pulse energy of 90μ*** the second stage,the 285 fs pulse is self-compressed in air-filled *** fine-tuning of the group delay dispersion(GDD)externally in a 3 mm window,a compressed pulse of 48 fs is *** leads to a 70-fold compression of the ps pulses at 2050 *** further used the sub-50 fs laser pulses to generate white light by focusing the pulse into a thin medium of YAG.

关键词： fiber amplifier compressor

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Optimization of Sectional Dimensions of I-Section Flange Beams and Recommendations for IS 808: 1989

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Open Journal of Civil Engineering 2016年第2期6卷 295-313页

作者： Himanshu Gaur krishna murari Biswajit Acharya Civil Engineering Department Jaypee University of Engineering & Technology Guna India Civil Engineering Department College of Engineering Rajasthan Technological University Kota India

This study covers optimization of I-sectional flange beams. Scope of this study is limited to medium weight flange beams of Table 1 of IS 808:1983 but it can be further extended for the other sections of this code. Best possible geometric shape of the cross-section is found for maximum performance of the beam with minimum material consumption. All possible loading conditions are considered in the study for which a beam in flexure undergoes in its life. ANSYS software program is used for the analysis and optimizing the sections. It is found that sections MB 125, MB 300 and MB 400 of Table 1 of IS 808 are not the optimum sections but other alternative of these cross-sections is available which within the same material consumption performs better than these sections of IS code.

关键词： Finite Element Analysis Flange Beam I-Section Optimization

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Relativistic Variation of Black Hole Temperature with Respect to Velocity in XRBs and AGN

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International Journal of Astronomy and Astrophysics 2017年第1期7卷 1-10页

作者： Dipo Mahto Alok Ranjan krishna murari Singh Department of Physics Marwari College T. M. B. University Bhagalpur India Department of Physics T. M. B. University Bhagalpur India

Stephen Hawking gave a formula for the temperature of black holes as given by . Some of the black holes have their spinning velocity from 50% to 99% of the velocity of light. Due to this velocity, the mass of black holes will vary which cause the variation in the temperature of black holes. In the present research article, we have applied the variation of mass with velocity to obtain the rate of change in temperature of the black holes with respect to velocity. We have also calculated their values for super dense stars like black holes existing in XRBs and AGN and concluded that for super dense stars like black holes of lower velocity as well as the velocity comparable to the velocity of light, the rate of change in temperature with respect to velocity is directly proportional to their velocities. This work will help us to find out the variation in temperature of different black holes spinning with different velocity percentage related to light speed and can be used as the references for other research works.

关键词： Hawking Temperature Black Holes XRBs AGN

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Half-a-century(1971–2020)of glacier shrinkage and climatic variability in the Bhaga basin,western Himalaya

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Journal of Mountain Science 2023年第3期20卷 299-324页

作者： DAS Suresh SHARMA Milap Chand murari Madhav krishna NÜSSER Marcus SCHMIDT Susanne Centre for the Study of Regional Development Jawaharlal Nehru UniversityNew Delhi 110067India National Geochronology Facility Inter-University Accelerator CentreNew Delhi 110067India Department of Geography South Asia Institute(SAI)Heidelberg UniversityHeidelberg 69115Germany Heidelberg Centre for the Environment(HCE) Heidelberg UniversityHeidelberg 69120Germany

Glacier shrinkage is a globally occurring ***-resolution change detection based on frequent mapping and monitoring of high-altitude glaciers is necessary to precisely evaluate future water availability and to understand glacier evolution under different climatic scenarios in the Hindukush-Karakoram-Himalayan(HKH)*** also holds true for the Bhaga basin of the western *** study investigates glacier and glacier lake changes in the Bhaga basin,over the last five decades based on satellite imagery including Corona KH4(1971),Landsat 7 Enhanced Thematic Mapper Plus(ETM+;2000),Linear Imaging Self-Scanning Sensor(LISS Ⅳ;2013),and Sentinel 2(2020).Regional temperature and precipitation trends were evaluated from gridded climatic datasets(1900–2020).In the Bhaga basin 306 glaciers(>0.2 km^(2))were mapped with a total area of 360.3±4.0 km^(2),of which 55.7±0.6 km^(2)was covered with debris in *** total glacier covered area decreased by∼8.2±1.5%(0.16±0.03%yr-1)during the entire observation period 1971–2020,with noticeable heterogeneity between tributary *** the past two decades(2000–2020),the deglaciation rate has increased significantly(0.25%yr-1)compared to the previous decades(1971–2000;0.12%yr-1).Glacier lake area increased by 0.6±0.1 km^(2)(0.012 km^(2)yr-1)between 1971 and *** NCEP/NCAR climatic data reveals an increase of 0.63℃in temperature and a decrease of 6.39 mm in precipitation for the period 1948–*** comparison,APHRODITE data shows an increasing trend in temperature of 1.14℃between 1961 and 2015 and decreasing trend in precipitation of 31 mm between 1951 and *** NCEP/NCAR and APHRODITE data reveal significant temperature increase and precipitation decrease since the 1990s,which have probably augmented ice loss in the Bhaga basin during the early 21st century.

关键词： Glacier change Remote sensing APHRODITE NCEP/NCAR reanalysis Climate change Western Himalaya

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Microfabricated intracortical extracellular matrix-microelectrodes for improving neural interfaces

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Microsystems & Nanoengineering 2018年第1期4卷 141-155页

作者： Wen Shen Suradip Das Flavia Vitale Andrew Richardson Akshay Ananthakrishnan Laura A.Struzyna Daniel P.Brown Naixin Song murari Ramkumar Timothy Lucas DKacy Cullen Brian Litt Mark G.Allen krishna P.Singh Center for Nanotechnology University of PennsylvaniaPhiladelphiaPA 19104USA Department of Neurosurgery Perelman School of MedicineUniversity of PennsylvaniaPhiladelphiaPA 19104USA Department of Neurology Perelman School of MedicineUniversity of PennsylvaniaPhiladelphiaPA 19104USA Department of Mechanical Engineering and Applied Mechanics School of Engineering and Applied ScienceUniversity of PennsylvaniaPhiladelphiaPA 19104USA Department of Bioengineering School of Engineering and Applied ScienceUniversity of PennsylvaniaPhiladelphiaPA 19104USA Department of Electrical and Systems Engineering School of Engineering and Applied ScienceUniversity of PennsylvaniaPhiladelphiaPA 19104USA Department of Materials Science and Engineering School of Engineering and Applied ScienceUniversity of PennsylvaniaPhiladelphiaPA 19104USA Present address:Department of Mechanical and Aerospace Engineering University of Texas at ArlingtonArlingtonTX 76019USA

Intracortical neural microelectrodes,which can directly interface with local neural microcircuits with high spatial and temporal resolution,are critical for neuroscience research,emerging clinical applications,and brain computer interfaces(BCI).However,clinical applications of these devices remain limited mostly by their inability to mitigate inflammatory reactions and support dense neuronal survival at their *** we report the development of microelectrodes primarily composed of extracellular matrix(ECM)proteins,which act as a bio-compatible and an electrochemical interface between the microelectrodes and physiological *** ECM-microelectrodes are batch fabricated using a novel combination of micro-transfer-molding and excimer laser micromachining to exhibit final dimensions comparable to those of commercial silicon-based *** are further integrated with a removable insertion stent which aids in intracortical *** from electrochemical models and in vivo recordings from the rat’s cortex indicate that ECM encapsulations have no significant effect on the electrochemical impedance characteristics of ECM-microelectrodes at neurologically relevant ***-microelectrodes are found to support a dense layer of neuronal somata and neurites on the electrode surface with high neuronal viability and exhibited markedly diminished neuroinflammation and glial scarring in early chronic experiments in rats.

关键词： markedly neural matrix

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