2,135 research outputs found
Use of ERTS-1 data in identification, classification, and mapping of salt-affected soils in California
There are no author-identified significant results in this report
An integrated study of earth resources in the State of California based on ERTS-1 and supporting aircraft data
There are no author-identified significant results in this report
Bostonia. Volume 11
Founded in 1900, Bostonia magazine is Boston University's main alumni publication, which covers alumni and student life, as well as university activities, events, and programs
Bostonia. Volume 12
Founded in 1900, Bostonia magazine is Boston University's main alumni publication, which covers alumni and student life, as well as university activities, events, and programs
Bostonia. Volume 3
Founded in 1900, Bostonia magazine is Boston University's main alumni publication, which covers alumni and student life, as well as university activities, events, and programs
Adaptive Optical Phase Estimation Using Time-Symmetric Quantum Smoothing
Quantum parameter estimation has many applications, from gravitational wave
detection to quantum key distribution. We present the first experimental
demonstration of the time-symmetric technique of quantum smoothing. We consider
both adaptive and non-adaptive quantum smoothing, and show that both are better
than their well-known time-asymmetric counterparts (quantum filtering). For the
problem of estimating a stochastically varying phase shift on a coherent beam,
our theory predicts that adaptive quantum smoothing (the best scheme) gives an
estimate with a mean-square error up to times smaller than that
from non-adaptive quantum filtering (the standard quantum limit). The
experimentally measured improvement is
Demonstration of the spatial separation of the entangled quantum side-bands of an optical field
Quantum optics experiments on "bright" beams typically probe correlations
between side-band modes. However the extra degree of freedom represented by
this dual mode picture is generally ignored. We demonstrate the experimental
operation of a device which can be used to separate the quantum side-bands of
an optical field. We use this device to explicitly demonstrate the quantum
entanglement between the side-bands of a squeezed beam
A wider Europe? The view from Russia, Belarus and Ukraine
On the evidence of national surveys conducted between 2000 and 2006, there is a declining sense of European self-identity in the three Slavic post-Soviet republics of Russia, Belarus and Ukraine. Attitudes towards the European Union and the possibility of membership are broadly supportive, but with a substantial proportion who find it difficult to express a view, and substantial proportions are poorly informed in comparison with the general public in EU member or prospective member countries. Those who are better informed are more likely to favour EU membership and vice versa. Generally, socioeconomic characteristics (except for age and region) are relatively poor predictors of support for EU membership as compared with attitudinal variables. But ‘Europeanness’ should not be seen as a given, and much will depend on whether EU member countries emphasize what is common to east and west or establish ‘new dividing lines’ in place of those of the cold war
Quantum noise limits to simultaneous quadrature amplitude and phase stabilization of solid-state lasers
A quantum mechanical model is formulated to describe the coupling between pump intensity noise and laser frequency noise in a solid-state laser. The model allows us to investigate the limiting effects of closed-loop stabilization schemes that utilize this coupling. Two schemes are considered: active control of the quadrature phase noise of the laser and active control of the amplitude noise of the laser. We show that the noise of the laser in the actively stabilized quadrature is ultimately limited by the vacuum noise introduced by the feedback beamsplitter in both schemes. In the case of active control of the quadrature phase noise, the noise is also limited by the intensity noise floor of the detection scheme. We also show that some sources of noise in the passively stabilized quadrature can be suppressed and that it is possible to achieve simultaneous quadrature amplitude and phase stabilization of a solid-state laser. However, the quantum mechanically driven noise in the passively stabilized quadrature cannot be suppressed. While this poses the ultimate limit to the noise in the passively stabilized quadrature, we show that it is experimentally feasible to observe squeezing directly generated by a solid-state laser using this technique
Temperature seasonality in the North American continental interior during the Early Eocene Climatic Optimum
Paleogene greenhouse climate equability has long been a paradox in
paleoclimate research. However, recent developments in proxy and modeling
methods have suggested that strong seasonality may be a feature of at least
some greenhouse Earth periods. Here we present the
first multi-proxy record of seasonal temperatures during the Paleogene from
paleofloras, paleosol geochemistry, and carbonate clumped isotope thermometry
in the Green River Basin (Wyoming, USA). These combined temperature records
allow for the reconstruction of past seasonality in the continental interior,
which shows that temperatures were warmer in all seasons during the peak
Early Eocene Climatic Optimum and that the mean annual range of temperatures was high,
similar to the modern value ( ∼ 26 °C). Proxy data and
downscaled Eocene regional climate model results suggest amplified
seasonality during greenhouse events. Increased seasonality reconstructed for
the early Eocene is similar in scope to the higher seasonal range predicted
by downscaled climate model ensembles for future high-CO2 emissions
scenarios. Overall, these data and model comparisons have substantial
implications for understanding greenhouse climates in general, and may be
important for predicting future seasonal climate regimes and their impacts in
continental regions.</p
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