Publications by authors named "Sergey Vasilyev"

25 Publications

  • Page 1 of 1

Respiratory adaptation to climate in modern humans and Upper Palaeolithic individuals from Sungir and Mladeč.

Sci Rep 2021 Apr 12;11(1):7997. Epub 2021 Apr 12.

Department of Anatomy, College of Osteopathic Medicine, Des Moines University, Des Moines, USA.

As our human ancestors migrated into Eurasia, they faced a considerably harsher climate, but the extent to which human cranial morphology has adapted to this climate is still debated. In particular, it remains unclear when such facial adaptations arose in human populations. Here, we explore climate-associated features of face shape in a worldwide modern human sample using 3D geometric morphometrics and a novel application of reduced rank regression. Based on these data, we assess climate adaptations in two crucial Upper Palaeolithic human fossils, Sungir and Mladeč, associated with a boreal-to-temperate climate. We found several aspects of facial shape, especially the relative dimensions of the external nose, internal nose and maxillary sinuses, that are strongly associated with temperature and humidity, even after accounting for autocorrelation due to geographical proximity of populations. For these features, both fossils revealed adaptations to a dry environment, with Sungir being strongly associated with cold temperatures and Mladeč with warm-to-hot temperatures. These results suggest relatively quick adaptative rates of facial morphology in Upper Palaeolithic Europe.
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http://dx.doi.org/10.1038/s41598-021-86830-xDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8042039PMC
April 2021

Kerr-lens mode-locked Cr:ZnS oscillator reaches the spectral span of an optical octave.

Opt Express 2021 Jan;29(2):2458-2465

We report, to the best of our knowledge, the first super-octave femtosecond polycrystalline Cr:ZnS laser at the central wavelength 2.4 µm. The laser is based on a non-polarizing astigmatic X-folded resonator with normal incidence mounting of the gain element. The chromatic dispersion of the resonator is controlled with a set of dispersive mirrors within one third of an optical octave over 2.05-2.6 µm range. The resonator's optics is highly reflective in the range 1.8-2.9 µm. The components of the oscillator's output spectrum at the wavelengths 1.6 µm and 3.2 µm are detected at -60 dB with respect to the main peak. Average power of few-cycle Kerr-lens mode-locked laser is 1.4 W at the pulse repetition frequency 79 MHz. That corresponds to 22% conversion of cw radiation of Er-doped fiber laser, which we used for optical pumping of the Cr:ZnS oscillator.
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http://dx.doi.org/10.1364/OE.411984DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7920525PMC
January 2021

A minimally destructive protocol for DNA extraction from ancient teeth.

Genome Res 2021 Mar 12;31(3):472-483. Epub 2021 Feb 12.

Institute of Archaeology, Research Centre for the Humanities, 1097 Budapest, Hungary.

Ancient DNA sampling methods-although optimized for efficient DNA extraction-are destructive, relying on drilling or cutting and powdering (parts of) bones and teeth. As the field of ancient DNA has grown, so have concerns about the impact of destructive sampling of the skeletal remains from which ancient DNA is obtained. Due to a particularly high concentration of endogenous DNA, the cementum of tooth roots is often targeted for ancient DNA sampling, but destructive sampling methods of the cementum often result in the loss of at least one entire root. Here, we present a minimally destructive method for extracting ancient DNA from dental cementum present on the surface of tooth roots. This method does not require destructive drilling or grinding, and, following extraction, the tooth remains safe to handle and suitable for most morphological studies, as well as other biochemical studies, such as radiocarbon dating. We extracted and sequenced ancient DNA from 30 teeth (and nine corresponding petrous bones) using this minimally destructive extraction method in addition to a typical tooth sampling method. We find that the minimally destructive method can provide ancient DNA that is of comparable quality to extracts produced from teeth that have undergone destructive sampling processes. Further, we find that a rigorous cleaning of the tooth surface combining diluted bleach and UV light irradiation seems sufficient to minimize external contaminants usually removed through the physical removal of a superficial layer when sampling through regular powdering methods.
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http://dx.doi.org/10.1101/gr.267534.120DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7919446PMC
March 2021

Genetic ancestry changes in Stone to Bronze Age transition in the East European plain.

Sci Adv 2021 Jan 20;7(4). Epub 2021 Jan 20.

Estonian Biocentre, Institute of Genomics, University of Tartu, Tartu 51010, Estonia.

The transition from Stone to Bronze Age in Central and Western Europe was a period of major population movements originating from the Ponto-Caspian Steppe. Here, we report new genome-wide sequence data from 30 individuals north of this area, from the understudied western part of present-day Russia, including 3 Stone Age hunter-gatherers (10,800 to 4250 cal BCE) and 26 Bronze Age farmers from the Corded Ware complex Fatyanovo Culture (2900 to 2050 cal BCE). We show that Eastern hunter-gatherer ancestry was present in northwestern Russia already from around 10,000 BCE. Furthermore, we see a change in ancestry with the arrival of farming-Fatyanovo Culture individuals were genetically similar to other Corded Ware cultures, carrying a mixture of Steppe and European early farmer ancestry. Thus, they likely originate from a fast migration toward the northeast from somewhere near modern-day Ukraine-the closest area where these ancestries coexisted from around 3000 BCE.
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http://dx.doi.org/10.1126/sciadv.abd6535DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7817100PMC
January 2021

Gravettian cranial morphology and human group affinities during the European Upper Palaeolithic.

Sci Rep 2020 12 14;10(1):21931. Epub 2020 Dec 14.

UMR 5199 PACEA, CNRS-Université de Bordeaux, Bâtiment B8, Allée Geoffroy Saint Hilaire, Pessac, 33615, France.

Archaeologically defined Upper Palaeolithic (UP, 45,000-10,000 years ago) "cultures" are often used as proxies to designate fossil populations. While recent genomic studies have partly clarified the complex relationship between European UP "cultures" and past population dynamics, they leave open numerous questions regarding the biological characterization of these human groups, especially regarding the Mid-UP period (MUP, 33,000-24,000 years ago), which encompasses a pan-European cultural mosaic (Gravettian) with several regional facies. Here, we analyse a large database of well-dated and well-preserved UP crania, including MUP specimens from South-West France (SWF) and Moravia, using 3D geometric morphometrics to test for human group affinities. Our results show that the Gravettian makers from these two regions form a remarkably phenetically homogeneous sample which is different from, and more homogeneous than, the Late UP sample. Those results are congruent with genomic studies indicating a genetic continuity within the Gravettian manufacturers and a discontinuity marked by the Last Glacial Maximum (LGM). Moreover, our study expands the geographical range of the MUP phenetic continuity to SWF, for which aDNA data are scarce, and clarifies the post-LGM European population structure in SWF, with a possible dual ancestry stemming from different LGM refugia.
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http://dx.doi.org/10.1038/s41598-020-78841-xDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7736346PMC
December 2020

Human auditory ossicles as an alternative optimal source of ancient DNA.

Genome Res 2020 03 25;30(3):427-436. Epub 2020 Feb 25.

Institute of Archaeological Sciences, Eötvös Loránd University, H-1088 Budapest, Hungary.

DNA recovery from ancient human remains has revolutionized our ability to reconstruct the genetic landscape of the past. Ancient DNA research has benefited from the identification of skeletal elements, such as the cochlear part of the osseous inner ear, that provides optimal contexts for DNA preservation; however, the rich genetic information obtained from the cochlea must be counterbalanced against the loss of morphological information caused by its sampling. Motivated by similarities in developmental processes and histological properties between the cochlea and auditory ossicles, we evaluate the ossicles as an alternative source of ancient DNA. We show that ossicles perform comparably to the cochlea in terms of DNA recovery, finding no substantial reduction in data quantity and minimal differences in data quality across preservation conditions. Ossicles can be sampled from intact skulls or disarticulated petrous bones without damage to surrounding bone, and we argue that they should be used when available to reduce damage to human remains. Our results identify another optimal skeletal element for ancient DNA analysis and add to a growing toolkit of sampling methods that help to better preserve skeletal remains for future research while maximizing the likelihood that ancient DNA analysis will produce useable results.
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http://dx.doi.org/10.1101/gr.260141.119DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7111520PMC
March 2020

Middle-IR frequency comb based on Cr:ZnS laser.

Opt Express 2019 Nov;27(24):35079-35087

We report, to the best of our knowledge, the first fully referenced Cr:ZnS optical frequency comb. The comb features few cycle output pulses with 3.25 W average power at 80 MHz repetition rate, spectrum spanning 60 THz in the middle-IR range 1.79-2.86 µm, and a small footprint (0.1 m), The spectral components used for the measurement of the comb's carrier envelope offset frequency were obtained directly inside the polycrystalline Cr:ZnS laser medium via intrinsic nonlinear interferometry. Using this scheme we stabilized the offset frequency of the comb with the residual phase noise of 75 mrads.
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http://dx.doi.org/10.1364/OE.27.035079DOI Listing
November 2019

The formation of human populations in South and Central Asia.

Science 2019 09;365(6457)

Earth Institute, University College Dublin, Dublin 4, Ireland.

By sequencing 523 ancient humans, we show that the primary source of ancestry in modern South Asians is a prehistoric genetic gradient between people related to early hunter-gatherers of Iran and Southeast Asia. After the Indus Valley Civilization's decline, its people mixed with individuals in the southeast to form one of the two main ancestral populations of South Asia, whose direct descendants live in southern India. Simultaneously, they mixed with descendants of Steppe pastoralists who, starting around 4000 years ago, spread via Central Asia to form the other main ancestral population. The Steppe ancestry in South Asia has the same profile as that in Bronze Age Eastern Europe, tracking a movement of people that affected both regions and that likely spread the distinctive features shared between Indo-Iranian and Balto-Slavic languages.
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http://dx.doi.org/10.1126/science.aat7487DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6822619PMC
September 2019

Palaeo-Eskimo genetic ancestry and the peopling of Chukotka and North America.

Nature 2019 06 5;570(7760):236-240. Epub 2019 Jun 5.

Department of Medicine, Northwestern University Feinberg School of Medicine, Chicago, IL, USA.

Much of the American Arctic was first settled 5,000 years ago, by groups of people known as Palaeo-Eskimos. They were subsequently joined and largely displaced around 1,000 years ago by ancestors of the present-day Inuit and Yup'ik. The genetic relationship between Palaeo-Eskimos and Native American, Inuit, Yup'ik and Aleut populations remains uncertain. Here we present genomic data for 48 ancient individuals from Chukotka, East Siberia, the Aleutian Islands, Alaska, and the Canadian Arctic. We co-analyse these data with data from present-day Alaskan Iñupiat and West Siberian populations and published genomes. Using methods based on rare-allele and haplotype sharing, as well as established techniques, we show that Palaeo-Eskimo-related ancestry is ubiquitous among people who speak Na-Dene and Eskimo-Aleut languages. We develop a comprehensive model for the Holocene peopling events of Chukotka and North America, and show that Na-Dene-speaking peoples, people of the Aleutian Islands, and Yup'ik and Inuit across the Arctic region all share ancestry from a single Palaeo-Eskimo-related Siberian source.
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http://dx.doi.org/10.1038/s41586-019-1251-yDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6942545PMC
June 2019

The population history of northeastern Siberia since the Pleistocene.

Nature 2019 06 5;570(7760):182-188. Epub 2019 Jun 5.

Institute of Archaeology and Ethnography of the Siberian Branch of the Russian Academy of Sciences, Novosibirsk, Russia.

Northeastern Siberia has been inhabited by humans for more than 40,000 years but its deep population history remains poorly understood. Here we investigate the late Pleistocene population history of northeastern Siberia through analyses of 34 newly recovered ancient genomes that date to between 31,000 and 600 years ago. We document complex population dynamics during this period, including at least three major migration events: an initial peopling by a previously unknown Palaeolithic population of 'Ancient North Siberians' who are distantly related to early West Eurasian hunter-gatherers; the arrival of East Asian-related peoples, which gave rise to 'Ancient Palaeo-Siberians' who are closely related to contemporary communities from far-northeastern Siberia (such as the Koryaks), as well as Native Americans; and a Holocene migration of other East Asian-related peoples, who we name 'Neo-Siberians', and from whom many contemporary Siberians are descended. Each of these population expansions largely replaced the earlier inhabitants, and ultimately generated the mosaic genetic make-up of contemporary peoples who inhabit a vast area across northern Eurasia and the Americas.
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http://dx.doi.org/10.1038/s41586-019-1279-zDOI Listing
June 2019

Multi-octave visible to long-wave IR femtosecond continuum generated in Cr:ZnS-GaSe tandem.

Opt Express 2019 May;27(11):16405-16413

We report a technique for generation of broad and coherent femtosecond (fs) continua that span several octaves from visible to long-wave IR parts of the spectrum (0.4-18 µm). The approach is based on simultaneous amplification of few-cycle pulses at 2.5 µm central wavelength at 80 MHz repetition rate, and augmentation of their spectrum via three-wave mixing in a tandem arrangement of polycrystalline Cr:ZnS and single crystal GaSe. The obtained average power levels include several mW in the 0.4-0.8 µm visible, 0.23 W in the 0.8-2 µm near-IR, up to 4 W in the 2-3 µm IR, and about 17 mW in the 3-18 µm long-wave IR bands, respectively. High brightness and mutual coherence of all parts of the continuum was confirmed by direct detections of the carrier envelope offset frequency of the master oscillator.
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http://dx.doi.org/10.1364/OE.27.016405DOI Listing
May 2019

Characterization of high-harmonic emission from ZnO up to 11  eV pumped with a Cr:ZnS high-repetition-rate source.

Opt Lett 2019 Jan;44(2):259-262

We report the measurement of high-order harmonics from a ZnO crystal with photon energies up to 11 eV generated by a high-repetition-rate femtosecond Cr:ZnS laser operating in the mid-infrared at 2-3 μm, delivering few-cycle pulses with multi-watt average power and multi-megawatt peak power. High-focus intensity is achieved in a single pass through the crystal without a buildup cavity or nanostructued pattern for field enhancement. We measure in excess of 10 high-harmonic photons/second.
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http://dx.doi.org/10.1364/OL.44.000259DOI Listing
January 2019

The genomic history of southeastern Europe.

Nature 2018 03 21;555(7695):197-203. Epub 2018 Feb 21.

Dipartimento di Biologia, Università di Firenze, 50122 Florence, Italy.

Farming was first introduced to Europe in the mid-seventh millennium bc, and was associated with migrants from Anatolia who settled in the southeast before spreading throughout Europe. Here, to understand the dynamics of this process, we analysed genome-wide ancient DNA data from 225 individuals who lived in southeastern Europe and surrounding regions between 12000 and 500 bc. We document a west-east cline of ancestry in indigenous hunter-gatherers and, in eastern Europe, the early stages in the formation of Bronze Age steppe ancestry. We show that the first farmers of northern and western Europe dispersed through southeastern Europe with limited hunter-gatherer admixture, but that some early groups in the southeast mixed extensively with hunter-gatherers without the sex-biased admixture that prevailed later in the north and west. We also show that southeastern Europe continued to be a nexus between east and west after the arrival of farmers, with intermittent genetic contact with steppe populations occurring up to 2,000 years earlier than the migrations from the steppe that ultimately replaced much of the population of northern Europe.
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http://dx.doi.org/10.1038/nature25778DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6091220PMC
March 2018

Ancient genomes show social and reproductive behavior of early Upper Paleolithic foragers.

Science 2017 11 5;358(6363):659-662. Epub 2017 Oct 5.

Centre for GeoGenetics, Natural History Museum of Denmark, University of Copenhagen, 1350 Copenhagen, Denmark.

Present-day hunter-gatherers (HGs) live in multilevel social groups essential to sustain a population structure characterized by limited levels of within-band relatedness and inbreeding. When these wider social networks evolved among HGs is unknown. To investigate whether the contemporary HG strategy was already present in the Upper Paleolithic, we used complete genome sequences from Sunghir, a site dated to ~34,000 years before the present, containing multiple anatomically modern human individuals. We show that individuals at Sunghir derive from a population of small effective size, with limited kinship and levels of inbreeding similar to HG populations. Our findings suggest that Upper Paleolithic social organization was similar to that of living HGs, with limited relatedness within residential groups embedded in a larger mating network.
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http://dx.doi.org/10.1126/science.aao1807DOI Listing
November 2017

Trepanation and enlarged parietal foramen on skulls from the Loyalty Islands (Melanesia).

Acta Med Hist Adriat 2017 06;15(1):67-72

Institute of Ethnology and Anthropology Russian Academy of Science, Centre of Physical Anthropology, Moscow, Russia.

The goal of this study is a comprehensive examination of openings discovered on two skulls in the collection of skeletal remains from the Loyalty Islands (Melanesia). The skull No. 1524 displayed an evidence of successful trepanation, and the skull No. 7985 revealed openings that were reminiscent of a trepanation, however, we are inclined to believe that in the latter case we are dealing with a rare genetic anomaly - enlarged parietal foramen.
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http://dx.doi.org/10.31952/amha.15.1.4DOI Listing
June 2017

140 W Cr:ZnSe laser system.

Opt Express 2016 Sep;24(18):21090-104

We report a significant breakthrough in the development of fiber-pumped high-power CW laser systems based on Cr2+:ZnS and Cr2+:ZnSe gain media. We demonstrate output power levels of up to 140 W near 2500 nm, and 32 W at 2940 nm with corresponding optical efficiencies of 62% and 29%. Our novel approach is based on rapid simultaneous scanning of the collinear laser mode and pump beam across the Cr:ZnS/Se gain element which allows us to virtually eliminate thermal lensing effects and obtain unprecedented levels of output power with very high optical-to-optical efficiency.
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http://dx.doi.org/10.1364/OE.24.021090DOI Listing
September 2016

Multi-Watt mid-IR femtosecond polycrystalline Cr(2+):ZnS and Cr(2+):ZnSe laser amplifiers with the spectrum spanning 2.0-2.6 µm.

Opt Express 2016 Jan;24(2):1616-23

We demonstrate efficient amplification of few-optical-cycle mid-IR pulses in single-pass continuously pumped laser amplifiers based on polycrystalline Cr(2+):ZnS and Cr(2+):ZnSe. The 1.7 W output of a Kerr-lens mode-locked master oscillator at 2.4 µm central wavelength, 79 MHz repetition rate was amplified to 7.1 W and 2.7 W in Cr(2+):ZnS and Cr(2+):ZnSe, respectively. High peak power of the input pulses (0.5 MW) and high nonlinearity of the amplifiers' gain media resulted in a significant shortening of the output pulses and in spectral broadening. Transform-limited 40 fs pulses of the master oscillator were compressed to about 27-30 fs. The spectrum of the pulses was broadened from 136 nm to 450 nm (at -3 dB level); the span of the spectra exceeds 600 nm at -10 dB level.
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http://dx.doi.org/10.1364/OE.24.001616DOI Listing
January 2016

Three optical cycle mid-IR Kerr-lens mode-locked polycrystalline Cr(2+):ZnS laser.

Opt Lett 2015 Nov;40(21):5054-7

We report Kerr-lens mode-locked polycrystalline Cr(2+):ZnS lasers at 2.4 μm central wavelength optimized for short pulse duration. By control of the second- and third-order dispersion within 500 nm bandwidth we obtained pulses of three optical cycles (<29  fs) at 100 MHz repetition rate with 0.44 W average power. The emission spectrum is 240 nm broad at -3  dB level and spans 950 nm at -30  dB level. Transform-limited 38 fs pulses were obtained at 300 MHz repetition rate with 700 mW average power. To the best of our knowledge these are the shortest reported to-date pulses from Cr(2+):ZnS and Cr(2+):ZnSe lasers.
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http://dx.doi.org/10.1364/OL.40.005054DOI Listing
November 2015

A New-Generation Fecal Immunochemical Test (FIT) Is Superior to Quaiac-based Test in Detecting Colorectal Neoplasia Among Colonoscopy Referral Patients.

Anticancer Res 2015 May;35(5):2873-80

Department of Clinical Research, Biohit Oyj, Helsinki, Finland Molecular Oncology Research Center, Barretos Cancer Hospital, Barretos, SP, Brazil

Aim: To compare a new-generation fecal immunochemical test (FIT) with the leading guaiac-based test in detection of fecal occult blood (FOB) in colonoscopy-referral patients.

Patients And Methods: A cohort of 300 patients referred for colonoscopy was examined by two different tests for FOB: ColonView quick test (CV) (FIT test for haemoglobin (Hb) and haemoglobin/haptoglobin (Hb/Hp) complex) and HemoccultSENSA (HS) (quaiac test for Hb). Three fecal samples were tested and all subjects were examined by diagnostic colonoscopy with biopsy verification. The test was interpreted positive if any of the three samples tested positive for Hb (HS test) and either Hb or Hb/Hp complex (CV test). The performance indicators (sensitivity (SE), specificity (SP), positive predictive value (PPV), negative predictive value (NPV) and area under the curve (AUC)) were calculated for both tests using three endpoints (adenoma (A), adenoma/carcinoma (A/AC) and carcinoma (AC)), collectively and were stratified according to tumor site. The two tests were compared regarding their sensitivity/specificity balance (AUC), using the receiver operating characteristics (ROC) comparison test.

Results: Colonoscopy (and biopsies) disclosed normal results in 85 (27.2%) subjects, A in 91 cases (30.3%) and AC in 95 (31.7%) patients. For the combined A+AC endpoint, the HS test had SE of 58.3% and SP of 96.5% (AUC=0.774), while the CV test had 97.2% SE and 85.8% SP (AUC=0.916) (p=0.0001). For the A endpoint, the difference between HS and CV was even more significant, AUC=0.637 and AUC=0.898, respectively (p=0.0001). In CV test, the Hb/Hp complex was 15% (93% vs. 78%) and 8% (96% vs. 88%) more sensitive than Hb alone, for the A and A+AC endpoints, respectively. Being more stable than Hb in the feces, the Hb/Hp complex detected 100% of the tumors in the proximal colon, as contrasted to only 41.2% and 52.9% by the Hb of HS and CV test, respectively (p=0.0001).

Conclusions: With its 100% SE and 95.3% SP for proximal colon neoplasia, as well as 98.2% SE and 95.3% SP for the distal neoplasia, ColonView is superior to current FIT tests on the market, recently shown to exhibit pooled SE of 79% and pooled SP of 94% for colorectal cancer (CRC) in a comprehensive meta-analysis. With these exceptional performance indicators, ColonView quick test should be the test-of-choice for CRC screening.
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May 2015

Kerr-lens mode-locked femtosecond polycrystalline Cr2+:ZnS and Cr2+:ZnSe lasers.

Opt Express 2014 Mar;22(5):5118-23

We report the first Kerr-lens mode-locked polycrystalline Cr(2+):ZnS and Cr(2+):ZnSe lasers, with pulse duration of 125 fs at a pulse repetition rate of 160 MHz, emitting around 2.3 - 2.4 µm. The mode-locked lasers were pumped by a radiation of 1550 nm Er-fiber amplifier seeded by semiconductor laser. The long-term stable Kerr-lens mode-locked laser operation with the output power of 30 mW (Cr(2+):ZnS) and 60 mW (Cr(2+):ZnSe) was obtained. We also demonstrate amplification of the fs laser pulse train in a cw pumped single-pass polycrystalline Cr(2+):ZnS laser amplifier.
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http://dx.doi.org/10.1364/OE.22.005118DOI Listing
March 2014

Robust, frequency-stable and accurate mid-IR laser spectrometer based on frequency comb metrology of quantum cascade lasers up-converted in orientation-patterned GaAs.

Opt Express 2013 Nov;21(22):27043-56

We demonstrate a robust and simple method for measurement, stabilization and tuning of the frequency of cw mid-infrared (MIR) lasers, in particular of quantum cascade lasers. The proof of principle is performed with a quantum cascade laser at 5.4 µm, which is upconverted to 1.2 µm by sum-frequency generation in orientation-patterned GaAs with the output of a standard high-power cw 1.5 µm fiber laser. Both the 1.2 µm and the 1.5 µm waves are measured by a standard Er:fiber frequency comb. Frequency measurement at the 100 kHz-level, stabilization to sub-10 kHz level, controlled frequency tuning and long-term stability are demonstrated.
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http://dx.doi.org/10.1364/OE.21.027043DOI Listing
November 2013

Spectrally narrow, long-term stable optical frequency reference based on a Eu3+:Y2SiO5 crystal at cryogenic temperature.

Phys Rev Lett 2011 Nov 21;107(22):223202. Epub 2011 Nov 21.

Institut für Experimentalphysik, Heinrich-Heine-Universität Düsseldorf, 40225 Düsseldorf, Germany.

Using an ultrastable continuous-wave laser at 580 nm we performed spectral hole burning of Eu(3+):Y(2)SiO(5) at a very high spectral resolution. The essential parameters determining the usefulness as a macroscopic frequency reference, linewidth, temperature sensitivity, and long-term stability, were characterized using a H-maser stabilized frequency comb. Spectral holes with a linewidth as low as 6 kHz were observed and the upper limit of the drift of the hole frequency was determined to be 5±3 mHz/s. We discuss the necessary requirements for achieving ultrahigh stability in laser frequency stabilization to these spectral holes.
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http://dx.doi.org/10.1103/PhysRevLett.107.223202DOI Listing
November 2011

Demonstration of high self-Raman laser performance of a diode-pumped SrMoO4:Nd3+ crystal.

Opt Lett 2009 Apr;34(7):1102-4

Laser Materials and Technology Research Center, General Physics Institute of RAS, Moscow, Russia.

Passively Q-switched self-Raman laser oscillations in the SrMoO4:Nd3+ crystal optically pumped by a laser diode (LD) at 804 nm are demonstrated for the first time to our knowledge. Output parameters of LD-pumped SrMoO4:Nd3+ laser were investigated in free-running, passively Q-switched, and self-Raman regimes of laser operation, over a wide range of pulse repetition rates (8.5-85 kHz). A pulse energy of 21 microJ was measured in the self-Raman regime at 1163 nm (first Stokes) wavelength, which is 6 times higher than that for the GdVO4:Nd3+ self-Raman laser of similar design.
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http://dx.doi.org/10.1364/ol.34.001102DOI Listing
April 2009

Broadly tunable single-frequency cw mid-infrared source with milliwatt-level output based on difference-frequency generation in orientation-patterned GaAs.

Opt Lett 2008 Jul;33(13):1413-5

Institut für Experimentalphysik, Universitätsstrasse 1, 40225 Düsseldorf, Germany.

A narrow-linewidth mid-IR source based on difference-frequency generation of an amplified 1.5 microm diode laser and a cw Tm-doped fiber laser in orientation-patterned (OP) GaAs has been developed and evaluated for spectroscopic applications. The source can be tuned to any frequency in the 7.6-8.2 microm range with an output power of 0.5 mW. The measured characteristics of the OP-GaAs sample demonstrate a high quality of the material.
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http://dx.doi.org/10.1364/ol.33.001413DOI Listing
July 2008

The history of tumescent anesthesia, part II: Vishnevsky's anesthesia from Russian textbooks, 1930 to 1970.

Aesthet Surg J 2002 Jan;22(1):46-51

Plastic Surgery Clinic, Everett, WA., Center for Plastic and Aesthetic Surgery, Chelyabinsk, Russia.

Although "tumescent anesthesia" has been described as a new technique, historical references reveal that in reality it has been used for decades all over the world. In "The History of Tumescent Anesthesia, Part I: From American Surgical Textbooks of the 1920s and 1930s" (Aesthetic Surg J 1998;18:353-357), Dr. Welch reported on early references to tumescent anesthesia in works published in the United States. In Part II, the authors report that tumescent anesthesia is very similar to a local anesthesia method, "Vishnevsky Local Anesthesia," widely known and used in Russia since the 1930s. (Aesthetic Surg J 2002;22:46-51.).
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http://dx.doi.org/10.1067/maj.2002.121959DOI Listing
January 2002