5941 research outputs found
Sort by
Unique collection @ Raman Research Institute Library : A case study
No full textRestricted Access, Book chapter from Best practices, case studies and management of content, information and knowledge in LIS profession, 2012, Ed by Nagappa V. Bakkannanavar, Published by Ess Ess Publications, New DelhiA research library collection is a key asset of the parent institution.
Raman Research Institute Library is a Repository of its scholarly
Information and strong special collections. Our main criteria
being collecting and exposing of any materials in all formats like
rare books, archives and manuscripts, audio, and video, and
digital, etc. A considerable amount of old and valuable material
in these formats faces risks of being permanently lost and hence
a beginning is made to identify, collect, preserve and at the same
time to expose more of these materials to boost their use in
learning and researc
Investigation of variability of iron emission lines in Centaurus X-3
No full textRestricted Access. An open-access version is available at arXiv.org (one of the alternative locations)We present the results obtained from a study of the variability of iron emission lines in the high mass X-ray binary pulsar Cen X-3 during the eclipse, eclipse-egress and out-of-eclipse phases using XMM-Newton observations. Three iron emission lines at 6.4 keV, 6.7 keV, and 6.97 keV are clearly detected in the spectrum of the pulsar during the entire observations, irrespective of different binary phases. The properties of these emission lines are investigated at different intensity levels. The flux level and equivalent width of the emission lines change during the eclipse, eclipse-egress and out-of-eclipse orbital phases. Based on the results obtained from the time resolved spectral analysis, it is understood that the most probable emitting region of 6.4 keV fluorescent line is very close to the neutron star whereas the other two lines are produced in a region that is far from the neutron star, probably in the highly photo-ionized wind of the companion star or in the accretion disk corona
Not shackled by history
No full textOpen AccessBiman Nath has captured the stories of ordinary people in extraordinary times in his latest novel, The Tattooed Faki
Implementing the Aharon-Vaidman quantum game with a young type photonic qutrit
No full textRestricted Access. An open-access version is available at arXiv.org (one of the alternative locations)The Aharon-Vaidman (AV) game exemplifies the advantage of using simple
quantum systems to outperform classical strategies. We present an experimental test of this
quantum advantage by using a three-state quantum system (qutrit) encoded in a spatial mode
of a single photon passing through a system of three slits. The preparation of a particular
state is controlled as the photon propagates through the slits by varying the number of open
slits and their respective phases. The measurements are achieved by placing detectors in the
specific positions in the near and far-field after the slits. This set of tools allowed us to perform
tomographic reconstructions of generalized qutrit states, and implement the quantum version
of the AV game with compelling evidence of the quantum advantage
The story of helium and birth of astrophysics
No full textTable of contentsWhat if one of the most thrilling stories in the history of science turned out to be wrong? Can urban legends creep into the hallowed grounds of scientific history? As incredible as it may sound, the story of one of the most important elements in modern times – helium - has been often misrepresented in books, encyclopedias, and online sources, despite the fact that archival materials tell a different story. Open the entry for Helium in any encyclopaedia and you will read a false story that has been repeated over the years. ‘Encyclopaedia Britannica’, for example, says that helium was discovered by the French astronomer Pierre Janssen while observing a total solar eclipse from India in 1868. Apparently he noticed something new in the spectrum of the sun, which he thought was the signature of an undiscovered element.
The truth is that Janssen never saw any sign of a new element during his observations in India. His reports and letters do not mention any such claim.
Other sources would have you believe that helium was jointly discovered by Janssen and Norman Lockyer, a British scientist, and that their discovery letters reached Paris the same day, one sent from India, and the other from England.
Again, the truth is completely different. Two letters from Lockyer and Janssen did reach Paris the same day in 1868, but their letters did not mention any new element. What they had discovered was a new way of observing the Sun without a solar eclipse. This would ultimately lead to the discovery of helium, in which Lockyer would play a prominent role, but not Janssen.
At the same time, Norman Robert Pogson, a disgruntled British astronomer stationed in India did notice something peculiar during the eclipse. He was the first one to notice something odd about the spectrum of the Sun that day, and his observations would prove crucial to Lockyer’s own investigations of helium. But Pogson’s report was never published in any peer reviewed journal and it languished on the desk of a local British officer in colonial India.
This book tells the real story behind the discovery of helium, along with biographical sketches of the scientists and descriptions of the milieu in which they worked. It will convey the excitement, confusion, and passion of nineteenth century scientists, using their own words, from their letters and reports.
“The Story of Helium and the Birth of Astrophysics” chronicles one of the most exciting discoveries ever made and explains why it also marked the birth of a new branch of science called ‘astrophysics.
A measure of non-Gaussianity for quantum states
No full textRestricted Access. An open-access version is available at arXiv.org (one of the alternative locations)We propose a measure of non-Gaussianity for quantum states of a system
of n oscillator modes. Our measure is based on the quasi-probability Q(α), α ∈ Cn.
Since any measure of non-Gaussianity is necessarily an attempt at making a quantitative
statement on the departure of the shape of theQfunction from Gaussian, any good
measure of non-Gaussianity should be invariant under transformations which do not
alter the shape of theQfunctions, namely displacements, passage through passive linear
systems, and uniform scaling of all the phase space variables: Q(α) → λ2nQ(λα).
Our measure which meets this ‘shape criterion’ is computed for a fewfamilies of states,
and the results are contrasted with existing measures of non-Gaussianity. The shape
criterion implies, in particular, that the non-Gaussianity of the photon-added thermal
states should be independent of temperature
Understanding the nature of cortical acto-myosin based active patterning machinery and its implications on the dynamics and the organization of cell surface molecules
No full textRestricted Access. An open-access version is available at arXiv.org (one of the alternative locations
A "Gaussian" for diffusion on the sphere
No full textRestricted Access.We present an analytical closed form expression, which gives a good approximate propagator for diffusion on the sphere. Our formula is the spherical counterpart of the Gaussian propagator for diffusion on the plane. While the analytical formula is derived using saddle point methods for short times, it works well even for intermediate times. Our formula goes beyond conventional "short time heat kernel expansions" in that it is nonperturbative in the spatial coordinate, a feature that is ideal for studying large deviations. Our work suggests a new and efficient algorithm for numerical integration of the diffusion equation on a sphere. We perform Monte Carlo simulations to compare the numerical efficiency of the new algorithm with the older Gaussian one