We suggest the use of broadband frequency modulation to construct a novel type of optical interferometer. This interferometer is insensitive to optical phase and allows measurement of the group velocity and group velocity dispersion without the need for short pulse apparatus.

We suggest a technique for using off-resonance spectral comb generation to produce broadband frequency-modulated (FM), and therefore amplitude-quieted, light. Results include closed-form formulas for the amplitudes and phases of all of the spectral components.

The Land Use Suitability (LUS) concept informs decision-making by providing stakeholders with integrated information about the economic, environmental, social and cultural consequences of land use choices. This paper addresses an application of the LUS concept: evaluating the suitability of land for sustained productivity subject to environmental constraints, as defined by water quality objectives. We refer to this application of the LUS concept as 'Productivity within Environmental Constraints' (PEC). A PEC assessment uses three indicators to evaluate land-water systems: 1) productive potential, describing the inherent productive and economic potential of land parcels; 2) relative contribution, describing the potential for a land parcel to contribute contaminants (relative to other land parcels) to downstream receiving environments; and 3) pressure, describing the contaminant load delivered to a receiving environment compared to the load that ensures that environmental objectives are met. The three indicators can be expressed categorically, mapped at catchment to national scales, and used to support strategic land assessments and plan land development and investment.

Mutations in bone morphogenetic protein 1 (BMP1) in humans or deletion of BMP1 and related protease tolloid like 1 (TLL1) in mice lead to osteogenesis imperfecta (OI). Here, we show progressive periodontal defects in mice in which both BMP1 and TLL1 have been conditionally ablated, including malformed periodontal ligament (PDL) (recently shown to play key roles in normal alveolar bone formation), significant loss in alveolar bone mass ( P < 0.01), and a sharp reduction in cellular cementum. Molecular mechanism studies revealed a dramatic increase in the uncleaved precursor of type I collagen (procollagen I) and a reduction in dentin matrix protein 1 (DMP1), which is partially responsible for defects in extracellular matrix (ECM) formation and mineralization. We also showed a marked increase in the expression of matrix metallopeptidase 13 (MMP13) and tartrate-resistant acid phosphatase (TRAP), leading to an acceleration in periodontal breakdown. Finally, we demonstrated that systemic application of antibiotics significantly improved the alveolar bone and PDL damage of the knockdown phenotype, which are thus shown to be partially secondary to pathogen-induced inflammation. Together, identification of the novel roles of BMP1 and TLL1 in maintaining homeostasis of periodontal formation, partly via biosynthetic processing of procollagen I and DMP1, provides novel insights into key contributions of the extracellular matrix environment to periodontal homeostasis and contributes toward understanding of the pathology of periodontitis.

We describe how electromagnetically induced transparency may be used to construct a non-traditional near-ideal quantum heat engine as constrained by the Second Law. The engine is pumped by a thermal reservoir that may be either hotter or colder than that of an exhaust reservoir, and also by a monochromatic laser. As output, it produces a bright narrow emission at line center of an otherwise absorbing transition.

We report clear experimental evidence for second harmonic generation at hard x-ray wavelengths. Using a 1.7 Å pumping beam generated by a free electron laser, we observe second harmonic generation in diamond. The generated second harmonic is of order 10 times the background radiation, scales quadratically with pump pulse energy, and is generated over a narrow phase-matching condition. Of importance for future experiments, our results indicate that it is possible to observe nonlinear x-ray processes in crystals at pump intensities exceeding 1016  W/cm2.

We report observation of x-ray and optical sum frequency generation. An ultrafast optical pulse drives charge oscillations to the chemical bonds in diamond. A co-propagating x-ray pulse probes the accompanying atomic-scale chemical bond distortion.

We report the first experimental evidence for second harmonic generation at hard x-ray wavelengths. A second harmonic beam is produced in a diamond crystal using a 1.77 Å pump from the SACLA free-electron laser.

We demonstrate a miniature source of long biphotons utilizing the cluster effect and double-pass pumping in a monolithic doubly resonant parametric down-converter. We obtain a biphoton correlation time of 17.1 ns with a generation rate of 1.10 x 10(5) biphotons/(s mW) and an estimated linewidth of 8.3 MHz. (C) 2012 American Institute of Physics. [http://dx.doi.org/10.1063/1.4740270]

Light-matter interactions are ubiquitous, and underpin a wide range of basic research fields and applied technologies. Although optical interactions have been intensively studied, their microscopic details are often poorly understood and have so far not been directly measurable. X-ray and optical wave mixing was proposed nearly half a century ago as an atomic-scale probe of optical interactions but has not yet been observed owing to a lack of sufficiently intense X-ray sources. Here we use an X-ray laser to demonstrate X-ray and optical sum-frequency generation. The underlying nonlinearity is a reciprocal-space probe of the optically induced charges and associated microscopic fields that arise in an illuminated material. To within the experimental errors, the measured efficiency is consistent with first-principles calculations of microscopic optical polarization in diamond. The ability to probe optical interactions on the atomic scale offers new opportunities in both basic and applied areas of science.

The death of Anthony E. (Tony) Siegman on October 7, 2011, was a profound shock to the worldwide optical science and laser community. An esteemed scientist and educator, Tony was also a kind and gentle man.

We experimentally and theoretically study the coincidence count rate for down-converted x-ray photons. Because of photoionization, parametric down-conversion at x-ray wavelengths generally involves loss and the theoretical description requires a Langevin approach. By working in a transmission geometry (Laue) rather than in the Bragg geometry of previous experiments, we obtain an improvement in the signal-to-noise ratio of 12.5, and find agreement between experiment and theory.

We show that polarization entangled photons at x-ray energies can be generated via spontaneous parametric down-conversion. Each of the four Bell states can be generated by choosing the angle of incidence and polarization of the pumping beam.

We use slow light and electromagnetically induced transparency to make and modulate single photons. Using spread spectrum technology we describe how a single photon may be hidden in an environment of noise photons. Article not available.

We calculate the properties of a biphoton source based on resonant backward-wave spontaneous parametric down conversion. We show that the biphotons are generated in a single longitudinal mode having a subnatural linewidth and a Glauber correlation time exceeding 65 ns.