Juggling with light

We discovered that when a pair of small particles is optically levitated, the particles execute a dance whose motion resembles the orbits of balls being juggled. This motion lies in a plane perpendicular to the polarization of the incident light. We ascribe the dance to a mechanism by which the dominant force on each particle cyclically alternates between radiation pressure and gravity as each particle takes turns eclipsing the other. We explain the plane of motion by considering the anisotropic scattering of polarized light at a curved interface.Comment: 5 pages, 5 figures, 7 supplementary video

Do Investors Learn About Analyst Accuracy?

We study the impact of analyst forecasts on prices to determine whether investors learn about analyst accuracy. Our test market is the crude oil futures market. Prices rise when analysts forecast a decrease (increase) in crude supplies. In the 15 minutes following supply realizations, prices rise (fall) when forecasts have been too high (low). In both the initial price action relative to forecasts and in the subsequent reaction relative to realized forecast errors, the price response is stronger for more accurate analysts. These price reactions imply that investors learn about analyst accuracy and trade accordingly.Financial Economics, Institutional and Behavioral Economics, Political Economy,

The Educational Emphases of Science Teachers in US Evangelical Protestant High Schools

I examine the educational emphases of science teachers in Evangelical Protestant (EP) schools, including (1) teaching basic content knowledge, (2) improving scientific reasoning skills, and (3) presenting real-world applications of science. Using a nationally representative sample of US ninth-graders, I find differences in these educational emphases between science teachers in EP schools and science teachers in secular private, Catholic, and public schools. I also find suggestive evidence that differences in STEM-related student outcomes across school sectors, which have been demonstrated in prior research, are associated with cross-sector differences in the emphases of science teachers

A study of chemical and cellular changes induced by Trichinella infections

The progressive host responses to the invading larvae of Trichinella spiralis and Trichinella pseudospiralis were monitored in the peritoneal cavity and skeletal muscles of mice;Activated peritoneal macrophages, obtained 15 days after oral infection of mice with T. spiralis, were found to secrete a transiently appearing protein (TAP). This protein has been purified by the use of polyacrylamide gel electrophoresis and isoelectrofocusing techniques. Chemical analysis revealed that TAP is acidic due to the high content of glutamic and aspartic acids. With 50% of its total amino acids being non-polar, this 50,000 dalton molecule tends to crystallize at its isoelectric point (5.7) and in deionized water. High-titer (1.5 x 10(\u27-5)) specific antibodies (IgG) to TAP were used to demonstrate that peritoneal macrophages are solely responsible for TAP production;The biological function of TAP is not known. It is not a plasma protein, a constituent substance in the cytoplasm of resident white blood cells, a membrane-bound molecule, an elastase or a plasminogen activator. However, TAP may have an immuno-regulatory function;T. spiralis and T. pseudospiralis infections of murine skeletal muscles were investigated using synchronous infections for histological studies and asynchronous infections for ultrastructural studies. The penetration of muscle cells by either species induces marked morphological changes in the host cells including: (1) an increase in the amount of endoplasmic reticulum, ribosomes, mitochondria and Golgi apparatus; (2) an increase in the size of muscle cell nuclei with enlarged nucleoli; and (3) degeneration and loss of myofilaments;In comparision with T. spiralis infected muscle cells, cells infected with T. pseudospiralis show a slower rate of myofilament degeneration and lighter basophilic staining and remain elongated and non-encapsulated;Tissue autoradiography plus various superimposed and concomitant infections with both species indicate that T. spiralis-infected muscle cells are intrinsically responsible for capsule formation. Encapsulation is independent of host fibroblasts and the presence of T. pseudospiralis. The lower content of guanosine and cytidine-rich RNA in the cytoplasm of T. pseudospiralis infected muscle cells suggests that collagen mRNA may not be present for the encapsulation processes

Hypofractionated SBRT versus conventionally fractionated EBRT for prostate cancer: comparison of PSA slope and nadir.

BackgroundPatients with early stage prostate cancer have a variety of curative radiotherapy options, including conventionally-fractionated external beam radiotherapy (CF-EBRT) and hypofractionated stereotactic body radiotherapy (SBRT). Although results of CF-EBRT are well known, the use of SBRT for prostate cancer is a more recent development, and long-term follow-up is not yet available. However, rapid post-treatment PSA decline and low PSA nadir have been linked to improved clinical outcomes. The purpose of this study was to compare the PSA kinetics between CF-EBRT and SBRT in newly diagnosed localized prostate cancer.Materials/methods75 patients with low to low-intermediate risk prostate cancer (T1-T2; GS 3 + 3, PSA < 20 or 3 + 4, PSA < 15) treated without hormones with CF-EBRT (>70.2 Gy, <76 Gy) to the prostate only, were identified from a prospectively collected cohort of patients treated at the University of California, San Francisco (1997-2012). Patients were excluded if they failed therapy by the Phoenix definition or had less than 1 year of follow-up or <3 PSAs. 43 patients who were treated with SBRT to the prostate to 38 Gy in 4 daily fractions also met the same criteria. PSA nadir and rate of change in PSA over time (slope) were calculated from the completion of RT to 1, 2 and 3 years post-RT.ResultsThe median PSA nadir and slope for CF-EBRT was 1.00, 0.72 and 0.60 ng/ml and -0.09, -0.04, -0.02 ng/ml/month, respectively, for durations of 1, 2 and 3 years post RT. Similarly, for SBRT, the median PSA nadirs and slopes were 0.70, 0.40, 0.24 ng and -0.09, -0.06, -0.05 ng/ml/month, respectively. The PSA slope for SBRT was greater than CF-EBRT (p < 0.05) at 2 and 3 years following RT, although similar during the first year. Similarly, PSA nadir was significantly lower for SBRT when compared to EBRT for years 2 and 3 (p < 0.005).ConclusionPatients treated with SBRT experienced a lower PSA nadir and greater rate of decline in PSA 2 and 3 years following completion of RT than with CF-EBRT, consistent with delivery of a higher bioequivalent dose. Although follow-up for SBRT is limited, the improved PSA kinetics over CF-EBRT are promising for improved biochemical control