Elu, loodus, teadus ja tehnoloogia
Author(s): Kohta Murase, Ranjan Laha, Shin’ichiro Ando, and Markus Ahlers
A class of very-heavy dark matter models could account for the ultra high energy neutrinos observed by IceCube and will be tested by future γ-ray detectors and neutrino telescopes.
[Phys. Rev. Lett. 115, 071301] Published Tue Aug 11, 2015
Human spaceflight and operations image of the week: ESA’s Cebreros deep-space tracking station reflecting environmentally friendly light
With the number of known circumbinary exoplanets now at 10, astronomers can begin to compare different systems and look for trends.
In the approach to perihelion over the past few weeks, Rosetta has been witnessing growing activity from Comet 67P/Churyumov–Gerasimenko, with one dramatic outburst event proving so powerful that it even pushed away the incoming solar wind.
Space science image of the week: Rosetta’s view upon arrival at the comet, on 6 August 2014, and exactly one year later
Most of the optics experiments done in beginning or advanced labs have ultrasonic analogs which can
be used to demonstrate much of what can be done in the optics labs. These analogs can be used as a
substitute for the corresponding optics experiments…
Finite size effects on classical ideal gas are revisited. The micro-canonical partition function for
a collection of ideal particles confined in a box is evaluated using Euler?Maclaurin?s as well as
Poisson’s summation formula. In Poisson’s summation…
The average energy per fermion in the case of a Fermi gas with any kinematic characteristic, trapped
under the most general power law potential in d -dimension has been calculated at zero temperature.
In a previous paper (Acharyya M 2010 Eur. J Phys….
A simple experimental setup for measuring Planck?s constant, using Landauer quantization of the
conductance between touching gold wires, is described. It consists of two gold wires with thickness
of ##IMG## [http://ej.iop.org/images/0143-0807/36/5/05…
Magnetic recording head theory is based on the Karlqvist approximation to solve the Laplace equation
over a polygonal domain that originates from a magnetostatic approach to describe the magnetic field
produced by the read/write head in the recording…
The linear variational method is a standard computational method in quantum mechanics and quantum
chemistry. As taught in most classes, the general guidance is to include as many basis functions as
practical in the variational wave function. However,…
A simple experimental setup for measuring Planck’s constant, using Landauer quantization of the
conductance between touching gold wires, is described. It consists of two gold wires with thickness
of ##IMG## [http://ej.iop.org/images/0143-0807/36/5/…
Like legendary superheroes, all space missions have origin stories. NASA’s Europa mission team recently wrote the final chapter of theirs, with their first team meeting.
Ten years after launch, NASA’s Mars Reconnaissance Orbiter has revealed the Red Planet’s diversity and activity, and its work is far from over.
An expected reduction in atmospheric ozone levels over the western U.S. was offset by natural atmospheric processes and pollutants crossing the Pacific Ocean from China.
Author(s): Keisuke Nagao, Tomoaki Inuzuka, Kazue Nishimoto, and Keiichi EdagawaIn situ high-resolution transmission electron microscopy has been used to spot quasicrystals in the act of growing.[Phys. Rev. Lett. 115, 075501] Published Mon Aug 10, 2015
Astronomers studying energy output in the nearby universe have confirmed that the energy produced today is only about half what it was 2 billion years ago.
Digital terrain mapping and mineralogical analysis of the features surrounding the deposit indicate that this one-time lakebed is no older than 3.6 billion years old.
The fact that scientists can see gravity perform the same in our solar system as it does in a distant star system helps confirm that the gravitational constant truly is universal.
NASA is launching an official Tumblr profile that will give Tumblr users a regular dose of space in a blog-like format through text, photos, videos and more.
Author(s): Tobias Haug, Philippe Klemm, Sebastian Bange, and John M. LuptonVisible light emission from silver and gold nanoparticle films irradiated with ultrashort infrared pulses is governed by hot electron recombination within the conduction band.[P…
Our week through the lens: 3-7 August 2015
The discovery explains the mystery of why many elliptical galaxies in the present-day universe are not ablaze with a higher rate of star birth.
Watch a replay of a Google+ Hangout with Rosetta and Philae experts held to celebrate the comet’s closest approach to the Sun
Low water levels in the Danube river have left ships to queue close to the town of Zimnicea in Romania.
The DSCOVR satellite’s series of test images reveals the fully illuminated “dark side” of the Moon never visible from our planet.
Agricultural fires in North Africa reduce the region’s rainfall during the dry season, according to a NASA study.
Striking 3-D detail highlights a towering mountain, the brightest spots and other features on dwarf planet Ceres in a new video from NASA’s Dawn mission.
Author(s): Kevin P. O’Keeffe, P. L. Krapivsky, and Steven H. Strogatz
An analysis of a model that might describe fireflies and neurons shows the path to synchronization occurring in groups of charge-and-fire oscillators.
[Phys. Rev. Lett. 115, 064101] Published Thu Aug 06, 2015
A prominent mountain with bright streaks on its steep slopes is especially fascinating to scientists.
Celebrating Rosetta’s first year at Comet 67P/Churyumov–Gerasimenko with a calendar of NavCam images
ESA’s Rosetta mission today celebrates one year at Comet 67P/Churyumov–Gerasimenko, with its closest approach to the Sun now just one week away.
Integration of Hamiltonian systems by reduction to action-angle variables has proven to be a
successful approach. However, when the solution depends on elliptic functions, the transformation to
action-angle variables may need to remain in implicit fo…
Integration of Hamiltonian systems by reduction to action-angle variables has proven to be a
successful approach. However, when the solution depends on elliptic functions, the transformation to
action-angle variables may need to remain in implicit fo…
An over-damped pendulum can be adopted as a mechanical analogue of an over-damped Josephson junction
(JJ). The basic equations leading to the driving torque versus the time average of the angular
frequency are studied. The mechanical analogue can be …
An over-damped pendulum can be adopted as a mechanical analogue of an over-damped Josephson junction
(JJ). The basic equations leading to the driving torque versus the time average of the angular
frequency are studied. The mechanical analogue can be …
A pedagogical account of some aspects of extreme value statistics (EVS) is presented from the
somewhat non-standard viewpoint of large deviation theory. We address the following problem: given a
set of N independent and identically distributed (i.i.d…
A pedagogical account of some aspects of extreme value statistics (EVS) is presented from the
somewhat non-standard viewpoint of large deviation theory. We address the following problem: given a
set of N independent and identically distributed (i.i.d…
In this paper, we report an experimental activity suitable for undergraduate students that makes
them question their ideas about locality and realism. The experiment here reported complements
previous educational approaches to Bell inequalities, sinc…
In this paper, we report an experimental activity suitable for undergraduate students that makes
them question their ideas about locality and realism. The experiment here reported complements
previous educational approaches to Bell inequalities, sinc…
In this paper we give a pedagogical explanation of coherence effects in non relativistic scattering
processes. Coherent scattering is important not only because it is a clear manifestation of the wave
character of the interaction in these regimes, bu…
In this paper we give a pedagogical explanation of coherence effects in non relativistic scattering
processes. Coherent scattering is important not only because it is a clear manifestation of the wave
character of the interaction in these regimes, bu…
In this paper, an advanced undergraduate RC circuit is studied in two different ways. The circuit is
a typical series RC circuit with a time-varying voltage source. The temporal profile of the voltage
is an isolated, Gaussian shaped pulse. The voltag…
In this paper, an advanced undergraduate RC circuit is studied in two different ways. The circuit is
a typical series RC circuit with a time-varying voltage source. The temporal profile of the voltage
is an isolated, Gaussian shaped pulse. The voltag…
On the three-year anniversary of the Mars landing of NASA’s Curiosity rover, NASA is unveiling two new online tools, inviting the public to help with its journey to Mars.
How did the very first life forms on Earth get an electrical boost? New laboratory experiments offer clues.
Author(s): A. Goban, C.-L. Hung, J. D. Hood, S.-P. Yu, J. A. Muniz, O. Painter, and H. J. Kimble
Trapping atoms near a photonic crystal waveguide produces strong atom-photon coupling that results in enhanced atomic emission of light.
[Phys. Rev. Lett. 115, 063601] Published Wed Aug 05, 2015
Scientists are performing laboratory studies to try to decipher what causes the giant storm’s swirl of reddish hues.
Scientists are performing laboratory studies to try to decipher what causes the giant storm’s swirl of reddish hues.
A new study has traced some members of the near-Earth object population back to their likely source — the Euphrosyne family of dark asteroids in the outer asteroid belt.
Europe’s latest weather satellite images Earth today
As part of a galactic archaeology study, astronomers discovered that the spatial distribution of the young stars around M81, M82, and NGC 3077 follows very closely that of their distribution of neutral hydrogen.
Astronomers have discovered that some neutron stars may rival black holes in their ability to accelerate powerful jets of material to nearly the speed of light.
Human spaceflight and operations image of the week: ESA’s New Norcia deep-space tracking station illuminated against the Australian night sky
We present a review of some aspects related to the experimental validity of the Sackur?Tetrode
equation for the entropy of monatomic ideal gases. First, we examine the main theoretical
assumptions which underlie the statistical derivation of the equa…
In this paper, we study theoretically the propagation of waves in locally periodic systems. To this
end, we employ a simple method based on the impedance function which is similar to the one used in
the transmission line theory. Results are presented…
The connection between fundamental interactions acting in molecules in a fluid and macroscopically
measured properties, such as the viscosity between colloidal particles coated with polymers, is
studied here. The role that hydrodynamic and Brownian f…
A mathematical model of a system consisting of a dc motor, mechanism converting the rotational
motion to the linear one and a single physical pendulum with the joint horizontally driven is
developed. Constant angular velocity of the crank is assumed….
We present a review of some aspects related to the experimental validity of the Sackur–Tetrode
equation for the entropy of monatomic ideal gases. First, we examine the main theoretical
assumptions which underlie the statistical derivation of the eq…
Sound resonance in pipes is investigated using a readily available setup consisting of a pipe,
loudspeaker, microphone, and laptop. Discrete Fourier transform is used to extract the amplitude and
phase spectra from the recorded sound enabling determi…
We propose a simple pedagogical way of introducing the Euler–MacLaurin summation formula in an
undergraduate course on statistical mechanics. The reason is that the students may feel more
comfortable and confident if they are able to deduce the mai…
There is a growing interest, both from the theoretical as well as experimental side, to test the
validity of the quantum superposition principle, and of theories which explicitly violate it by
adding nonlinear terms to the Schrödinger equation. We r…
In this paper we present a simple experimental set-up to study the fall of a rigid rod, which can
freely rotate around an articulated joint at the lowest point. The experimental set-up permits
preparation of a laboratory session for physics or engine…
Basic formulae and results of glacier physics appearing in glaciology textbooks can be derived from
first principles introduced in algebra-based first year physics courses. We discuss the maximum
thickness of alpine glaciers and ice sheets and the re…
The general formulation of a determinate solution problem is deduced for the transverse vibrations
of a thin loaded rod. The vibration frequencies of a thin homogeneous rod carrying a concentrated
mass as a function of the load’s position and mass …
The interaction between a plane wave and a classical charged particle is reviewed in this paper. A
matrix formulation is used to derive the relativistic motion of the particle due to the Lorentz
force of a spatially homogeneous time-harmonic radiatio…
Astronomers may have found the source of a particularly hard-to-spot group of near-Earth asteroids, thanks to a once-dormant NASA space telescope.
Author(s): F. Huber, S. Matencio, A. J. Weymouth, C. Ocal, E. Barrena, and F. J. Giessibl
An improved take on an existing approach provides intramolecular imaging of molecules adsorbed on a solid surface at room temperature.
[Phys. Rev. Lett. 115, 066101] Published Mon Aug 03, 2015
Author(s): J. H. Bin, W. J. Ma, H. Y. Wang, M. J. V. Streeter, C. Kreuzer, D. Kiefer, M. Yeung, S. Cousens, P. S. Foster, B. Dromey, X. Q. Yan, R. Ramis, J. Meyer-ter-Vehn, M. Zepf, and J. Schreiber
Laser pulses that have passed through a carbon-nanotube foam are ideally suited to accelerate ions.
[Phys. Rev. Lett. 115, 064801] Published Mon Aug 03, 2015
Space science image of the week: Explore the Atlantis Chaos region of Mars in images and a new fly-through movie
Scientists have found that about 30 percent of the Milky Way’s stars have traveled a long way from the orbits in which they were born.
The new composite image of the Lagoon Nebula’s central region shows churning funnels of gas and energetic star formation.
Teachers and students from rural schools in South Africa and Italy are benefiting from an ESA-supported project that enriches education through satcoms.
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The breakup of a liquid jet into spherical droplets via the Rayleigh?Plateau instability is a common
and fundamental part of fluid mechanics. However, teaching this instability in a laboratory setting
is challenging, requiring sophisticated methods t…
The doubling of the gravitational light-bending effect, in comparison with Newton’s theoretical
prediction, is explained by the space curvature.
Quantum dynamics means studying the evolution of an initially prescribed wave function. This is
analytically tractable for special wavefunctions for the simplest of the situations—free particle
and simple harmonic oscillator. The purely anharmonic …
The paper revisits Rüchardt’s experiment and the two-chamber variant of Clark and Katz, where the
oscillating motion of a freely sliding piston involves the adiabatic exponent of the gas enclosed in
a thermally isolated chamber. While the common t…
Description unavailable
The breakup of a liquid jet into spherical droplets via the Rayleigh–Plateau instability is a common
and fundamental part of fluid mechanics. However, teaching this instability in a laboratory setting
is challenging, requiring sophisticated methods…
Mysterious objects called brown dwarfs are sometimes called “failed stars.”
New NASA video shows a rotating, two-lobed asteroid that recently flew past Earth.
Two decades into the study of planets that orbit other stars, scientists recall that the discovery of the first such planet seemed almost unbelievable at the time.
Our week through the lens: 27-31 July 2015
The microlensing technique can find more distant and colder planets in long-period orbits that other methods cannot detect.
The European Space Agency’s Philae lander has discovered complex organic molecules on the surface of Comet 67P.
Registration open for ESTEC Open Day on Sunday 4 October: your chance to visit ESA’s technical heart
Earth observation image of the week: a Sentinel-2 image of lakes on the southern side of the Italian Alps, also featured on the Earth from Space video programme
A new NASA study has concluded California accumulated a debt of about 20 inches of precipitation between 2012 and 2015.
Using NASA’s Spitzer Space Telescope, astronomers have confirmed the discovery of the nearest rocky planet outside our solar system, larger than Earth and a potential gold mine of science data.
Complex molecules that could be key building blocks of life, the daily rise and fall of temperature, and an assessment of the surface properties and internal structure of the comet are just some of the highlights of the first scientific analysis of the data returned by Rosetta’s lander Philae last November.
Author(s): Carl L. Rodriguez, Meagan Morscher, Bharath Pattabiraman, Sourav Chatterjee, Carl-Johan Haster, and Frederic A. RasioMergers of binary black holes from dense star clusters may be promising sources of gravitational waves.[Phys. Rev. Lett. 115…
Join us Friday, 31 July, at 10:00 CEST for the ‘Earth from Space’ video programme. This week features a Sentinel-2A image of northern Italy
Dubbed HD 219134b, this exoplanet, which orbits too close to its star to sustain life, is a mere 21 light-years away.
Narrow, curved red lines on Tethys’ surface are among the most unusual color features on Saturn’s moons to be revealed by Cassini’s cameras.
ESA astronaut Paolo Nespoli will be heading for space a third time, as part of Expeditions 52 and 53 to the International Space Station. He will be launched on a Soyuz vehicle in May 2017 on a five-month mission.
Musicians, composers and audio buffs are invited to help celebrate 40 years of ESA’s tracking station network. Create some truly cosmic sound and you may win impressive prizes, including a trip to our anniversary gala event in Spain.
Unexplained arc-shaped, reddish streaks are visible on the surface of Saturn’s icy moon Tethys in new, enhanced-color images from NASA’s Cassini spacecraft.
Author(s): C. Chang et al.The Dark Energy Survey has generated a map of invisible dark matter by observing tiny gravitationally induced distortions in the images of distant galaxies.[Phys. Rev. Lett. 115, 051301] Published Wed Jul 29, 2015
Author(s): David P. Franke, Florian M. Hrubesch, Markus Künzl, Hans-Werner Becker, Kohei M. Itoh, Martin Stutzmann, Felix Hoehne, Lukas Dreher, and Martin S. Brandt
The interaction between the nuclear quadrupole moment of Arsenic and an electric field gradient can be manipulated by applying an elastic strain to the host silicon crystal. This technique could allow for mechanical tuning of qubits.
[Phys. Rev. Lett. 115, 057601] Published Wed Jul 29, 2015