Reply to "Comment on 'Precision measurement of the Casimir-Lifshitz force in a fluid'"

We have reviewed the Comment of Geyer et al. [arXiv:0708.1548] concerning our recent work [Phys. Rev. A 75, 060102 (R) (2007)], and while we disagree with their criticisms, we acknowledge them for giving us the opportunity to add interesting addition material and a more detailed description of our experiment. We describe further our calculation and explain why a more sophisticated model is not warranted. We also present detailed experiments on the effects of electrostatic forces in our measurements and show that the contribution due to work function differences is small and that the residual electrostatic force is dominated by trapped charges and external fields. Finally, we estimate the effect of double layer interactions. These additional calculations and measurements support our original conclusion that the experimental results are consistent with the Lifshitz theory

Effects of Excessive Natural Mulch on Development, Yield, and Structure of Native Grassland

Prairie vegetation is so universally mowed, grazed, or burned that little information has been recorded on its behavior under complete protection. Climax grassland, when grazed lightly or even moderately, may retain essentially its natural composition over extremely long periods (16, 18). But aside from observation there is little information upon the unusual and rare phenomenon of complete protection of grassland from disturbance over a considerable period of time

Weed Control in Windbreaks.

2 p

Energy Spectrum Evolution of a Diffuse Field in Elastic Body Caused by Weak Nonlinearity

We study the evolution of diffuse elastodynamic spectral energy density under the influence of weak nonlinearity. It is shown that the rate of change of this quantity is given by a convolution of the linear energy at two frequencies. Quantitative estimates are given for sample aluminum and fused silica blocks of experimental interest.Comment: 9 pages, 3 figures; revised for better presentatio

Local Ferroelectricity in SrTiO_3 Thin Films

The temperature-dependent polarization of SrTiO_3 thin films is investigated using confocal scanning optical microscopy. A homogeneous out-of-plane and inhomogeneous in-plane ferroelectric phase are identified from images of the linear electrooptic response. Both hysteretic and non-hysteretic behavior are observed under a dc bias field. Unlike classical transitions in bulk ferroelectrics, local ferroelectricity is observed at temperatures far above the dielectric permittivity maximum. The results demonstrate the utility of local probe experiments in understanding inhomogeneous ferroelectrics.Comment: 8 pages, 3 figures, accepted for publication in PR

Research and investigation of geology, mineral, and water resources of Maryland

The authors have identified the following significant results. Field work in Baltimore County revealed that the signature returns of serpentinitic and nonserpentinitic rocks correlates with the vegetation cover and land use pattern. In Maryland Piedmont, bedrock lithology and structure are enhanced only to the extent that land use is geologically dictated. Two prominent sets of linear features are detected on ERTS-1 imagery at N 45 deg E and N 20 deg E. Beaches of Chesapeake Bay are classified as broad and narrow beaches based on the width of the backshore zone. It is shown by comparing historical shorelines of Ocean City, from the inlet to the Maryland-Delaware line that reversal zones of erosion and accretion occur at different locations for different periods. High reflectance levels (high marsh-high topographic areas) for the lower Eastern Shore are found to be distributed as two distinct trending linear ridge systems. Observations of MSS band 5 dated 9 April 1974 exhibited an unique sedimentation pattern for Chesapeake Bay. Following a 1.5 inch rainfall, heavy concentration of suspended sediments is observed on the imagery, particularly in the area of the turbidity maximum

Hydrogen Isocyanide in Comet 73P/Schwassmann-Wachmann (Fragment B)

We present a sensitive 3-sigma upper limit of 1.1% for the HNC/HCN abundance ratio in comet 73P/Schwassmann-Wachmann (Fragment B), obtained on May 10-11, 2006 using Caltech Submillimeter Observatory (CSO). This limit is a factor of ~7 lower than the values measured previously in moderately active comets at 1 AU from the Sun. Comet 73P/Schwassmann-Wachmann was depleted in most volatile species, except of HCN. The low HNC/HCN ratio thus argues against HNC production from polymers produced from HCN. However, thermal degradation of macromolecules, or polymers, produced from ammonia and carbon compounds, such as acetylene, methane, or ethane appears a plausible explanation for the observed variations of the HNC/HCN ratio in moderately active comets, including the very low ratio in comet 73P/Schwassmann-Wachmann reported here. Similar polymers have been invoked previously to explain anomalous 14N/15N ratios measured in cometary CN.Comment: 6 pages, 5 figures, 2 table

Water service delivery challenges in a small South African municipality: Identifying and exploring key elements and relationships in a complex social-ecological system

South Africa is a developing country undergoing social and ecological transformation. Water service delivery (i) exemplifies the challenge of improvement and transformation towards a more socially and ecologically just situation, and (ii) can usefully be viewed as a complex social-ecological system (C-SES) in the search for ‘just transitions’. Household water security problems associated with water service delivery in South Africa are recognisably intractable, multi-scaled, comprising many actors and elements and having no single solution. There is a global and South African trend towards systemic approaches to addressing such complex water challenges. However, the steps required to take a systemic approach are seldom explicit. This paper presents the analytical process of defining boundaries, identifying elements and exploring relationships between elements as the foundational step in a study of the Makana Local Municipality water service delivery C-SES in the Eastern Cape Province of South Africa. The resulting narrative and heuristics provide a clear systemic basis from which to research the emergence, practice and social learning process of a civil society organisation (Water for Dignity) seeking to confront water service delivery issues in the Makana Local Municipality.Keywords: complex adaptive systems, systems inquiry, household water service delivery, civil society organisatio

Quasi Two-dimensional Transfer of Elastic Waves

A theory for multiple scattering of elastic waves is presented in a random medium bounded by two ideal free surfaces, whose horizontal size is infinite and whose transverse size is smaller than the mean free path of the waves. This geometry is relevant for seismic wave propagation in the Earth crust. We derive a time-dependent, quasi-2D radiative transfer equation, that describes the coupling of the eigenmodes of the layer (surface Rayleigh waves, SH waves, and Lamb waves). Expressions are found that relate the small-scale fluctuations to the life time of the modes and to their coupling rates. We discuss a diffusion approximation that simplifies the mathematics of this model significantly, and which should apply at large lapse times. Finally, coherent backscattering is studied within the quasi-2D radiative transfer equation for different source and detection configurations.Comment: REVTeX, 36 pages with 10 figures. Submitted to Phys. Rev.