Transition radiation caused by a chiral plate

A simple calculation is made of the electromagnetic field radiated due to a charged particle traversing a plate of chiral material. The transition radiation from this chiral plate is round to differ from the usual dielectrie transition radiation. Discussion is presented placing in evidence the characteristics of the radiation and comments are made concerning the possible applicability of the transition radiation mechanism

Impacts of Cattle Grazing Management on Sediment and Phosphorus Loads in Surface Waters

In 2001 (yr 1), 2002 (yr 2), and 2003 (yr 3), three blocks of five 1-ac paddocks were grazed by beef cows on hills at the Iowa State University Rhodes Research and Demonstration Farm to determine the effects of grazing management on phosphorus (P) and sediment runoff from pastureland. Grazing management treatments included an ungrazed control (UG), summer hay harvest with winter stockpiled grazing (HS), grazing by continuous stocking to a residual sward height of 2 in. (2C), rotational stocking to a residual sward height of 2 in. (2R), and rotational stocking to a residual sward height of 4 in (4R). At four times (late spring, mid-summer, early autumn, and early the subsequent spring) in each year, rainfall simulations were conducted at 6 sites within each paddock. Rainfall simulators dripped at a rate of 2.8 in./hr over a 5.4-ft2 area for a period of 1.5 hours. Runoff was collected and analyzed for total sediment, total P, and total soluble P. Simultaneous to each rainfall simulation, ground cover, penetration resistance, surface roughness, slope, the contents of P and moisture of the soil, sward height and forage mass were measured. Sediment flow was not affected by forage management practice. There was no difference between UG, HS, 4R in the amount of total P or soluble P lost in runoff, but greater amounts of total and soluble P were lost from 2C and 2R than from the other management practices (P\u3c0.05). A greater amount of sediment was lost from the pastures during the late spring period than during other parts of the year (P\u3c0.05). Losses of sediment, total P, and soluble P from pastures can be controlled by suitable grazing management practices

A current review of causation and management of functional myopia

A current review of the proposed causes and controls concerning the management of functional myopia is discussed. Nutritional-Disease, Mechanical-Anatomical, Environmental, and Genetic theories are reviewed. Topics concerning the controls of myopia include orthokeratology, vision training, surgery, pharmaceuticals and bifocals. A macroscopic theory of myopia development is presented and the merits of the various methods of control are evaluated

A Preliminary Report on the Frequency of Scrapie Susceptibility Alleles in Hampshire Sheep

Blood samples were collected from a total of 201 animals in five purebred Hampshire sheep flocks. DNA was isolated from the samples, and the protein-coding region of the prion protein gene was amplified using the polymerase chain reaction. The allelic frequencies of the prion protein codons 171 and 136 were determined. Results revealed that the codon 171 alleles Q, R, and H were present at frequencies of 72%, 27% and 1%, respectively. A subset of samples (n=48) was randomly selected for codon 136 genotyping. The codon 136 V allele, an allele not frequently observed in Suffolk sheep, was present in animals from three of five flocks at a frequency ranging from 7 to 33% of the animals tested within each flock. These data comprise the first report on the prevalence of scrapie susceptibility alleles in Hampshire sheep

Aerodynamic Mixing Downstream from Line Source of Heat in High-intensity Sound Field

Theory and measurement showed that the heat wake downstream from a line source is displaced by a transverse standing sound wave in a manner similar to a flag waving in a harmonic mode. With a 147 db, 104 cps standing wave, time-mean temperatures were reduced by an order of magnitude except near the displacement-pattern nodal points. The theory showed that a 161 db, 520 cps standing wave considerably increased the mixing in both the time-mean and instantaneous senses

On the Near-Zone Inverse Doppler Effect

Attention is invited to the recently discovered inverse Doppler effect which occurs in the near-zone field of an antenna emitting a continuous wave. On approaching the antenna, the received signal is blue-shifted in the far zone and then red-shifted in the near zone; and on receding from the antenna, the received signal is blue-shifted in the near zone and then red-shifted in the far zone. Calculations are presented for the case where the antenna is a simple dipole. It is shown that this effect gives not only the vector velocity of the moving receiver but also its range, i.e., its distance from the antenna

Runaway evaporation for optically dressed atoms

Forced evaporative cooling in a far-off-resonance optical dipole trap is proved to be an efficient method to produce fermionic- or bosonic-degenerated gases. However in most of the experiences, the reduction of the potential height occurs with a diminution of the collision elastic rate. Taking advantage of a long-living excited state, like in two-electron atoms, I propose a new scheme, based on an optical knife, where the forced evaporation can be driven independently of the trap confinement. In this context, the runaway regime might be achieved leading to a substantial improvement of the cooling efficiency. The comparison with the different methods for forced evaporation is discussed in the presence or not of three-body recombination losses

Inelastic and elastic collision rates for triplet states of ultracold strontium

We report measurement of the inelastic and elastic collision rates for ^{88}Sr atoms in the (5s5p)^3P_0 state in a crossed-beam optical dipole trap. This is the first measurement of ultracold collision properties of a ^3P_0 level in an alkaline-earth atom or atom with similar electronic structure. Since the (5s5p)^3P_0 state is the lowest level of the triplet manifold, large loss rates indicate the importance of principle-quantum-number-changing collisions at short range. We also provide an estimate of the collisional loss rates for the (5s5p){^3P_2} state.Comment: 4 pages 5 figure

Why Some Well-planned and Community-based ICTD Interventions Fail

Despite being community-based and well planned, some ICTD interventions fall short of expectations. The present analysis seeks to advance the understanding of the effectiveness of the ICTD initiative by exploring some of the reasons for failure. In this article three such case studies were identified and issues with their outcomes analyzed. Each project enjoyed some successes, but also suffered from some anomalous outcomes. A common characteristic of the projects is that the people who executed the program were not included in the program design. The goal of this article is to advance the debate about the effectiveness of ICTD initiatives and dispute the notion that community-based interventions carried out in conjunction with local partners assure success. The main lesson is that even a nearly imperceptible deviation from the full inclusion of all relevant parties in every aspect of the project can result in large deviations from the expected outcomes.</p

Photoassociative spectroscopy at long range in ultracold strontium

We report photoassociative spectroscopy of $^{88}$Sr$_2$ in a magneto-optical trap operating on the ${^1S_0}\to{^3P_1}$ intercombination line at 689 nm. Photoassociative transitions are driven with a laser red-detuned by 600-2400 MHz from the ${^1S_0}\to{^1P_1}$ atomic resonance at 461 nm. Photoassociation takes place at extremely large internuclear separation, and the photoassociative spectrum is strongly affected by relativistic retardation. A fit of the transition frequencies determines the ${^1P_1}$ atomic lifetime ($\tau=5.22 \pm 0.03$ ns) and resolves a discrepancy between experiment and recent theoretical calculations.Comment: 4 pages, 4 figures, submitte