327 research outputs found
Heartbeat of the Southern Oscillation explains ENSO climatic resonances
The El Ni~no-Southern Oscillation (ENSO) nonlinear oscillator phenomenon has a far reaching
influence on the climate and human activities. The up to 10 year quasi-period cycle of the El Ni~no and
subsequent La Ni~na is known to be dominated in the tropics by nonlinear physical interaction of wind with
the equatorial waveguide in the Pacific. Long-term cyclic phenomena do not feature in the current theory
of the ENSO process. We update the theory by assessing low (>10 years) and high (<10 years) frequency
coupling using evidence across tropical, extratropical, and Pacific basin scales. We analyze observations and
model simulations with a highly accurate method called Dominant Frequency State Analysis (DFSA) to
provide evidence of stable ENSO features. The observational data sets of the Southern Oscillation Index
(SOI), North Pacific Index Anomaly, and ENSO Sea Surface Temperature Anomaly, as well as a theoretical
model all confirm the existence of long-term and short-term climatic cycles of the ENSO process with
resonance frequencies of {2.5, 3.8, 5, 12–14, 61–75, 180} years. This fundamental result shows long-term and
short-term signal coupling with mode locking across the dominant ENSO dynamics. These dominant
oscillation frequency dynamics, defined as ENSO frequency states, contain a stable attractor with three
frequencies in resonance allowing us to coin the term Heartbeat of the Southern Oscillation due to its
characteristic shape. We predict future ENSO states based on a stable hysteresis scenario of short-term and
long-term ENSO oscillations over the next century
Two-particle correlations in azimuthal angle and pseudorapidity in inelastic p + p interactions at the CERN Super Proton Synchrotron
Multiplicity and transverse momentum fluctuations in inelastic proton–proton interactions at the CERN Super Proton Synchrotron
Measurements of pi(+/-), K-+/-, K-S(0), Lambda and proton production in proton-carbon interactions at 31 GeV/c with the NA61/SHINE spectrometer at the CERN SPS
Factorization and Lie point symmetries of general Lienard-type equation in the complex plane
We present a variational approach to a general Lienard-type equation in order
to linearize it and, as an example, the Van der Pol oscillator is discussed.
The new equation which is almost linear is factorized. The point symmetries of
the deformed equation are also discussed and the two-dimensional Lie algebraic
generators are obtained
Generation of coherent terahertz pulses in Ruby at room temperature
We have shown that a coherently driven solid state medium can potentially
produce strong controllable short pulses of THz radiation. The high efficiency
of the technique is based on excitation of maximal THz coherence by applying
resonant optical pulses to the medium. The excited coherence in the medium is
connected to macroscopic polarization coupled to THz radiation. We have
performed detailed simulations by solving the coupled density matrix and
Maxwell equations. By using a simple -type energy scheme for ruby, we have
demonstrated that the energy of generated THz pulses ranges from hundreds of
pico-Joules to nano-Joules at room temperature and micro-Joules at liquid
helium temperature, with pulse durations from picoseconds to tens of
nanoseconds. We have also suggested a coherent ruby source that lases on two
optical wavelengths and simultaneously generates THz radiation. We discussed
also possibilities of extension of the technique to different solid-state
materials
Measurements of production and inelastic cross sections for p+C, p+Be, and p+Al at 60 GeV/c and p+C and p+Be at 120 GeV/c
This paper presents measurements of production cross sections and inelastic cross sections for the
following reactions: 60 GeV=c protons with C, Be, Al targets and 120 GeV=c protons with C and Be
targets. The analysis is performed using the NA61/SHINE spectrometer at the CERN Super Proton
Synchrotron. First measurements are obtained using protons at 120 GeV=c, while the results for protons at
60 GeV=c are compared with previously published measurements. These interaction cross section
measurements are critical inputs for neutrino flux prediction in current and future accelerator-based
long-baseline neutrino experiments.Authors:A. Aduszkiewicz,15 E. V. Andronov,21 T. Antićić,3 V. Babkin,19 M. Baszczyk,13 S. Bhosale,10 A. Blondel,23 M. Bogomilov,2
A. Brandin,20 A. Bravar,23 W. Bryliński,17 J. Brzychczyk,12 M. Buryakov,19 O. Busygina,18 A. Bzdak,13 H. Cherif,6
M. Ćirković,22 M. Csanad,7 J. Cybowska,17 T. Czopowicz,17 A. Damyanova,23 N. Davis,10 M. Deliyergiyev,9 M. Deveaux,6
A. Dmitriev,19 W. Dominik,15 P. Dorosz,13 J. Dumarchez,4 R. Engel,5 G. A. Feofilov,21 L. Fields,24 Z. Fodor,7,16
A. Garibov,1 M. Gaździcki,6,9 O. Golosov,20 M. Golubeva,18 K. Grebieszkow,17 F. Guber,18 A. Haesler,23 S. N. Igolkin,21
S. Ilieva,2 A. Ivashkin,18 S. R. Johnson,26 K. Kadija,3 E. Kaptur,14 N. Kargin,20 E. Kashirin,20 M. Kiełbowicz,10
V. A. Kireyeu,19 V. Klochkov,6 V. I. Kolesnikov,19 D. Kolev,2 A. Korzenev,23 V. N. Kovalenko,21 K. Kowalik,11
S. Kowalski,14 M. Koziel,6 A. Krasnoperov,19 W. Kucewicz,13 M. Kuich,15 A. Kurepin,18 D. Larsen,12 A. László,7
T. V. Lazareva,21 M. Lewicki,16 K. Łojek,12 B. Łysakowski,14 V. V. Lyubushkin,19 M. Maćkowiak-Pawłowska,17
Z. Majka,12 B. Maksiak,11 A. I. Malakhov,19 A. Marchionni,24 A. Marcinek,10 A. D. Marino,26 K. Marton,7 H.-J. Mathes,5
T. Matulewicz,15 V. Matveev,19 G. L. Melkumov,19 A. O. Merzlaya,12 B. Messerly,27 Ł. Mik,13 G. B. Mills,25
S. Morozov,18,20 S. Mrówczyński,9 Y. Nagai ,26 M. Naskręt,16 V. Ozvenchuk,10 V. Paolone,27 M. Pavin,4,3 O. Petukhov,18
R. Płaneta,12 P. Podlaski,15 B. A. Popov,19,4 B. Porfy,7 M. Posiadała-Zezula,15 D. S. Prokhorova,21 D. Pszczel,11
S. Puławski,14 J. Puzović,22 M. Ravonel,23 R. Renfordt,6 E. Richter-Wąs,12 D. Röhrich,8 E. Rondio,11 M. Roth,5
B. T. Rumberger,26 M. Rumyantsev,19 A. Rustamov,1,6 M. Rybczynski,9 A. Rybicki,10 A. Sadovsky,18 K. Schmidt,14
I. Selyuzhenkov,20 A. Yu. Seryakov,21 P. Seyboth,9 M. Słodkowski,17 A. Snoch,6 P. Staszel,12 G. Stefanek,9 J. Stepaniak,11
M. Strikhanov,20 H. Ströbele,6 T. Šuša,3 A. Taranenko,20 A. Tefelska,17 D. Tefelski,17 V. Tereshchenko,19 A. Toia,6
R. Tsenov,2 L. Turko,16 R. Ulrich,5 M. Unger,5 F. F. Valiev,21 D. Veberič,5 V. V. Vechernin,21 A. Wickremasinghe,27
Z.Włodarczyk,9 A.Wojtaszek-Szwarc,9 K. Wójcik,14 O.Wyszyński,12 L. Zambelli,4 E. D. Zimmerman,26 and R. Zwaska24
(NA61/SHINE Collaboration)
1National Nuclear Research Center, Baku, Azerbaijan
2Faculty of Physics, University of Sofia, Sofia, Bulgaria
3Rud¯er Bošković Institute, Zagreb, Croatia
4LPNHE, University of Paris VI and VII, Paris, France
5Karlsruhe Institute of Technology, Karlsruhe, Germany
6University of Frankfurt, Frankfurt, Germany
7Wigner Research Centre for Physics of the Hungarian Academy of Sciences, Budapest, Hungary
8University of Bergen, Bergen, Norway
9Jan Kochanowski University in Kielce, Poland
10Institute of Nuclear Physics, Polish Academy of Sciences, Cracow, Poland
11National Centre for Nuclear Research, Warsaw, Poland
12Jagiellonian University, Cracow, Poland
13AGH—University of Science and Technology, Cracow, Poland
14University of Silesia, Katowice, Poland
15University of Warsaw, Warsaw, Poland
16University of Wrocław, Wrocław, Poland
17Warsaw University of Technology, Warsaw, Poland
18Institute for Nuclear Research, Moscow, Russia
19Joint Institute for Nuclear Research, Dubna, Russia
20National Research Nuclear University (Moscow Engineering Physics Institute), Moscow, Russia
21St. Petersburg State University, St. Petersburg, Russia
22University of Belgrade, Belgrade, Serbia
23University of Geneva, Geneva, Switzerland
24Fermilab, Batavia, Illinois, USA
25Los Alamos National Laboratory, Los Alamos, New Mexico, USA
26University of Colorado, Boulder, Colorado, USA
27University of Pittsburgh, Pittsburgh, Pennsylvania, US
HS 0139+0559, HS 0229+8016, HS 0506+7725, and HS 0642+5049 : four new long-period cataclysmic variables
We present time-resolved optical spectroscopy and photometry of four relatively bright (V ∼ 14.0−15.5) long-period cataclysmic variables(CVs) discovered in the Hamburg Quasar Survey: HS 0139+0559, HS 0229+8016, HS 0506+7725, and HS 0642+5049. Their respective orbital periods, 243.69
± 0.49 min, 232.550 ± 0.049 min, 212.7 ± 0.2 min, and 225.90
± 0.23 min are determined from radial velocity and photometric variability studies. HS 0506+7725 is characterised by strong Balmer and He emission lines, short-period (∼10−20 min) flickering, and weak X-ray emission in the ROSAT All Sky Survey. The detection of a deep low state (B 18.5) identifies HS 0506+7725 as a member of the VY Scl
stars. HS 0139+0559, HS 0229+8016, and HS 0642+5049 display thick-disc like spectra and no or only weak flickering activity. HS 0139+0559 and HS 0229+8016 exhibit clean quasi-sinusoidal radial velocity variations of their emission lines but no or very little orbital photometricvariability. In contrast, we detect no radial velocity variation in HS 0642+5049 but a noticeable orbital brightness variation. We identify all three systems either as UX UMa-type novalike variables or as Z Cam-type dwarf novae. Our identification of these four new systems underlines that the currently known sample of CVs is rather incomplete even for bright objects. The four new systems add to the clustering of orbital periods in the 3−4 h range found in the sample of HQS selected CVs, and we discuss the large incidence of magnetic CVs and VY Scl/SW Sex stars found in this period range among the known population of CVs
The First Detection of Blue Straggler Stars in the Milky Way Bulge
We report the first detections of Blue Straggler Stars (BSS) in the bulge of
the Milky Way galaxy. Proper motions from extensive space-based observations
along a single sight-line allow us to separate a sufficiently clean and
well-characterized bulge sample that we are able to detect a small population
of bulge objects in the region of the color-magnitude diagram commonly occupied
young objects and blue strgglers. However, variability measurements of these
objects clearly establish that a fraction of them are blue stragglers. Out of
the 42 objects found in this region of the color-magnitude diagram, we estimate
that at least 18 are genuine BSS. We normalize the BSS population by our
estimate of the number of horizontal branch stars in the bulge in order to
compare the bulge to other stellar systems. The BSS fraction is clearly
discrepant from that found in stellar clusters. The blue straggler population
of dwarf spheroidals remains a subject of debate; some authors claim an
anticorrelation between the normalised blue straggler fraction and integrated
light. If this trend is real, then the bulge may extend it by three orders of
magnitude in mass. Conversely, we find that the genuinely young (~5Gy or
younger) population in the bulge, must be at most 3.4% under the most
conservative scenario for the BSS population.Comment: ApJ in press; 25 pages, 6 figures, 2 table
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