Comment on "Observation of a Push Force on the End Face of a Nanometer Silica Filament Exerted by Outgoing Light" [PRL 101, 243601 (2008)]

A brief discussion is given on the recent experiment of She et al. [Phys. Rev. Lett. 101, 243601 (2008), arXiv:0806.2442], in relation to the Abraham-Minkowski energy-momentum problem.Comment: 1 page latex. The text is partially reformulated. To appear as a Comment in Phys. Rev. Let

Possible relationships between solar activity and atmospheric constituents

The large body of data on solar variations and atmospheric constituents collected between 1902 and 1953 by the Astrophysical Observatory of the Smithsonian Institution (APO) was examined. Short-term variations in amounts of atmospheric aerosols and water vapor due to seasonal changes, volcanic activity, air pollution, and frontal activity are discussed. Preliminary evidence indicates that increased solar activity is at times associated with a decrease in attenuation due to airborne particulates

Dust Storms in Space?

Primarily from the Pioneer 8 and 9 results, it is concluded that the flux of picogram sized dust particles near the earth's orbit has been constant to within the observational limits over three years of observation. In particular, since dust streams are not observed, they cannot explain microphone detected events. However, the possibility of rare events due to dust blown directly off a cometary nucleus (such as that reported for Comet Bennett) cannot be completely ruled out

Theory of Optical Tweezers

We derive a partial-wave (Mie) expansion of the axial force exerted on a transparent sphere by a laser beam focused through a high numerical aperture objective. The results hold throughout the range of interest for practical applications. The ray optics limit is shown to follow from the Mie expansion by size averaging. Numerical plots show large deviations from ray optics near the focal region and oscillatory behavior (explained in terms of a simple interferometer picture) of the force as a function of the size parameter. Available experimental data favor the present model over previous ones.Comment: 4 pages, 3 figure

Application of Lippmann interference photography to data storage

Lippmann's interference photography is an elegant process to record coloured images in the volume of a sensitive material. We propose to use this technique for wavelength multiplexed data storage in a page-oriented approach. Using computer simulations, we demonstrate that the capacities reached with this technique are similar to those reached by volume holographic data storage

Complications of Intrathecal Baclofen Pump: Prevention and Cure

Increasingly, spasticity is managed with surgically implanted Intrathecal Baclofen pumps. Intrathecal Baclofen pump revision surgery unrelated to programmable pump end-of-life is not uncommon, requiring special attention during pre-, intra-, and postoperative management. We aimed to identify and describe complications of Intrathecal Baclofen pump as well as to report avoidance and management of complications. Methods and Materials. Through 2002–2006, at the department of neurosurgery, Henry Ford and Oakwood Health Systems, Intrathecal Baclofen pumps were implanted in 44 patients: 24 children versus 20 adults; 30 “primary-implant-patients”; 14 “revision-only patients”. We evaluated reasons for revision surgeries and diagnostic workup requirements. Results. Eight primary-implant-patients required 14 revisions and 7 of revision-only patients needed 13 procedures. Seven patients with slowly increasing baclofen-resistant spasticity had either (i) unsuspected pump-catheter connector defects, (ii) an X-ray-documented pump-catheter connector defect, (iii) X-ray-demonstrated fractured catheter with intrathecal fragment. Implant infections occurred in 4 cases. Scintigraphy revealed occult CSF leakage N=1 and intrinsic pump failure N=1. Conclusion. Intrathecal Baclofen pumps, although very gratifying, have a high, technique-related complication incidence during implant life. Meticulous technique, high clinical suspicion, appropriate workup, and timely surgical management can reduce surgical complications of Intrathecal Baclofen pump implantation

On the Relation between Solar Activity and Clear-Sky Terrestrial Irradiance

The Mauna Loa Observatory record of direct-beam solar irradiance measurements for the years 1958-2010 is analysed to investigate the variation of clear-sky terrestrial insolation with solar activity over more than four solar cycles. The raw irradiance data exhibit a marked seasonal cycle, extended periods of lower irradiance due to emissions of volcanic aerosols, and a long-term decrease in atmospheric transmission independent of solar activity. After correcting for these effects, it is found that clear-sky terrestrial irradiance typically varies by about 0.2 +/- 0.1% over the course of the solar cycle, a change of the same order of magnitude as the variations of the total solar irradiance above the atmosphere. An investigation of changes in the clear-sky atmospheric transmission fails to find a significant trend with sunspot number. Hence there is no evidence for a yet unknown effect amplifying variations of clear-sky irradiance with solar activity.Comment: 16 pages, 7 figures, in press at Solar Physics; minor changes to the text to match final published versio

Self-assembly in patchy proteins: From transient networks to attractive glasses

Dynamic properties of crowded protein solutions are difficult to predict and control. This for example considerably limits our ability to create stable and injectable formulations of proteins or peptides at high concentrations. Another physiologically relevant case is presbyopia, or age-related farsightedness, where the pathological stiffening of the eye lens can be related to a liquid-solid transition of the protein mixtures inside the eye lens cells1. It is thus essential to achieve a quantitative understanding of the link between the molecular structure of the proteins and the interactions between them, and how these interactions influence the stability, dynamics and flow properties of the solutions as a function of their concentration. Here we show how we can use a combination of advanced characterization techniques1-4 such as neutron spin echo, small-angle scattering, 3D cross correlation light scattering and microrheology, combined with state-of-the-art computer simulations to assess and predict interparticle interactions and their impact on the dynamics and flow behavior of crowded protein solutions. We particularly point out the enormous influence of weak attractive interactions known to exist between many globular proteins, and demonstrate the dramatic effect of an interaction potential anisotropy such as attractive patches4 and shape anisotropy on the dynamic properties. [1] G. Foffi, G. Savin, S. Bucciarelli, N. Dorsaz, G. Thurston, A. Stradner, P. Schurtenberger; A Hard Sphere-Like Glass Transition in Eye Lens Alpha Crystallin Solutions ; Proc. Natl. Acad. Sci. U. S. A., 111, 16748-16753 (2014). [2] F. Cardinaux, E. Zaccarelli, A. Stradner, S. Bucciarelli, B. Farago, S. Egelhaaf, F. Sciortino, P. Schurtenberger; Cluster-driven dynamical arrest in concentrated lysozyme solutions J. Phys. Chem. B, 115, 7227 (2011). [3] S. Bucciarelli, L. Casal-Dujat, C. De Michele, F. Sciortino, J. Dhont, J. Bergenholtz, B. Farago, P. Schurtenberger, and A. Stradner; Unusual Dynamics of Concentration Fluctuations in Solutions of Weakly Attractive Globular Proteins ; The Journal of Physical Chemistry Letters, 6, 4470-4474 (2015). [4] S. Bucciarelli, J. S. Myung, B. Farago, S. Das, G. A. Viegenthart, O. Holderer, R. G. Winkler, P. Schurtenberger, G. Gompper, and A. Stradner; Dramatic Influence of Attractions on Short-Time Protein Diffusion under Crowded Conditions ; Science Advances, 2, e1601432 (2016)