Is there a Jordan geometry underlying quantum physics?

There have been several propositions for a geometric and essentially non-linear formulation of quantum mechanics. From a purely mathematical point of view, the point of view of Jordan algebra theory might give new strength to such approaches: there is a ``Jordan geometry'' belonging to the Jordan part of the algebra of observables, in the same way as Lie groups belong to the Lie part. Both the Lie geometry and the Jordan geometry are well-adapted to describe certain features of quantum theory. We concentrate here on the mathematical description of the Jordan geometry and raise some questions concerning possible relations with foundational issues of quantum theory.Comment: 30 page

Deposition nucleation on mineral dust particles: a case against classical nucleation theory with the assumption of a single contact angle

Deposition nucleation on two mineral species, kaolinite and illite, was studied using a flow cell coupled to an optical microscope. The results show that the <i>S</i><sub>ice</sub> conditions when ice first nucleated, defined as the onset <i>S</i><sub>ice</sub> (<i>S</i><sub>ice,onset</sub>), is a strong function of the surface area available for nucleation, varying from 100% to 125% at temperatures between 242 and 239 K. The surface area dependent data could not be described accurately using classical nucleation theory and the assumption of a single contact angle (defined here as the single-α model). These results suggest that caution should be applied when using contact angles determined from <i>S</i><sub>ice,onset</sub> data and the single-α model. In contrast to the single-α model, the active site model, the deterministic model, and a model with a distribution of contact angles fit the data within experimental uncertainties. Parameters from the fits to the data are presented

Comment on "Correlation between Compact Radio Lout Quasars and Ultrahigh Energy Cosmic Rays"

In a recent paper, Farrar and Biermann argue that there is a strong correlation between the direction of the five highest-energy cosmic-ray events and compact, radio-loud quasars. This Comment shows that this analysis contains several inconsistencies and errors so that the significance of any such correlation is certainly greatly overestimated and perhaps nonexistent.Comment: 2 pages, REVTE

Indication of electron neutrino appearance from an accelerator-produced off-axis muon neutrino beam

The T2K experiment observes indications of nu(mu) -> nu(mu) e appearance in data accumulated with 1.43 x 10(20) protons on target. Six events pass all selection criteria at the far detector. In a three-flavor neutrino oscillation scenario with |Delta m(23)(2)| = 2.4 x 10(-3) eV(2), sin(2)2 theta(23) = 1 and sin(2)2 theta(13) = 0, the expected number of such events is 1.5 +/- 0.3(syst). Under this hypothesis, the probability to observe six or more candidate events is 7 x 10(-3), equivalent to 2.5 sigma significance. At 90% C.L., the data are consistent with 0.03(0.04) < sin(2)2 theta(13) < 0.28(0.34) for delta(CP) = 0 and a normal (inverted) hierarchy

Technical Note: New methodology for measuring viscosities in small volumes characteristic of environmental chamber particle samples

Herein, a method for the determination of viscosities of small sample volumes is introduced, with important implications for the viscosity determination of particle samples from environmental chambers (used to simulate atmospheric conditions). The amount of sample needed is &lt; 1 μl, and the technique is capable of determining viscosities (η) ranging between 10&lt;sup&gt;−3&lt;/sup&gt; and 10&lt;sup&gt;3&lt;/sup&gt; Pascal seconds (Pa s) in samples that cover a range of chemical properties and with real-time relative humidity and temperature control; hence, the technique should be well-suited for determining the viscosities, under atmospherically relevant conditions, of particles collected from environmental chambers. In this technique, supermicron particles are first deposited on an inert hydrophobic substrate. Then, insoluble beads (~1 μm in diameter) are embedded in the particles. Next, a flow of gas is introduced over the particles, which generates a shear stress on the particle surfaces. The sample responds to this shear stress by generating internal circulations, which are quantified with an optical microscope by monitoring the movement of the beads. The rate of internal circulation is shown to be a function of particle viscosity but independent of the particle material for a wide range of organic and organic-water samples. A calibration curve is constructed from the experimental data that relates the rate of internal circulation to particle viscosity, and this calibration curve is successfully used to predict viscosities in multicomponent organic mixtures

Deliquescence, efflorescence, and phase miscibility of mixed particles of ammonium sulfate and isoprene-derived secondary organic material

The hygroscopic phase transitions of ammonium sulfate mixed with isoprene-derived secondary organic material were investigated in aerosol experiments. The organic material was produced by isoprene photo-oxidation at 40% and 60% relative humidity. The low volatility fraction of the photo-oxidation products condensed onto ammonium sulfate particles. The particle-phase organic material had oxygen-to-carbon ratios of 0.67 to 0.74 (±0.2) for mass concentrations of 20 to 30 μg m&lt;sup&gt;&amp;minus;3&lt;/sup&gt;. The deliquescence, efflorescence, and phase miscibility of the mixed particles were investigated using a dual arm tandem differential mobility analyzer. The isoprene photo-oxidation products induced deviations in behavior relative to pure ammonium sulfate. Compared to an efflorescence relative humidity (ERH) of 30 to 35% for pure ammonium sulfate, efflorescence was eliminated for aqueous particles having organic volume fractions &lt;i&gt;&amp;varepsilon;&lt;/i&gt; of 0.6 and greater. Compared to a deliquescence relative humidity (DRH) of 80% for pure ammonium sulfate, the DRH steadily decreased with increasing &lt;i&gt;&amp;varepsilon;&lt;/i&gt;, approaching a DRH of 40% for &lt;i&gt;&amp;varepsilon;&lt;/i&gt; of 0.9. Parameterizations of the DRH(&lt;i&gt;&amp;varepsilon;&lt;/i&gt;) and ERH(&lt;i&gt;&amp;varepsilon;&lt;/i&gt;) curves were as follows: DRH(&lt;i&gt;&amp;varepsilon;&lt;/i&gt;)= &amp;sum;&lt;sub&gt;&lt;i&gt;i&lt;/i&gt;&lt;/sub&gt; &lt;i&gt;c&lt;/i&gt;&lt;sub&gt;&lt;i&gt;i,d&lt;/i&gt;&lt;/sub&gt; &lt;i&gt;&amp;varepsilon;&lt;/i&gt;&lt;sup&gt;&lt;i&gt;i&lt;/i&gt;&lt;/sup&gt; valid for 0 &amp;le; &lt;i&gt;&amp;varepsilon;&lt;/i&gt; &amp;le;0.86 and ERH(&lt;i&gt;&amp;varepsilon;&lt;/i&gt;)= &amp;sum; &lt;sub&gt;&lt;i&gt;i&lt;/i&gt;&lt;/sub&gt; &lt;i&gt;c&lt;/i&gt;&lt;sub&gt;&lt;i&gt;i,e&lt;/i&gt;&lt;/sub&gt; &lt;i&gt;&amp;varepsilon;&lt;/i&gt;&lt;sup&gt;&lt;i&gt;i&lt;/i&gt;&lt;/sup&gt; valid for 0 &amp;le; &lt;i&gt;&amp;varepsilon;&lt;/i&gt; &amp;le; 0.55 for the coefficients &lt;i&gt;c&lt;/i&gt;&lt;sub&gt;0,&lt;i&gt;d&lt;/i&gt;&lt;/sub&gt;= 80.67, &lt;i&gt;c&lt;/i&gt;&lt;sub&gt;0,&lt;i&gt;e&lt;/i&gt;&lt;/sub&gt; = 28.35, &lt;i&gt;c&lt;/i&gt;&lt;sub&gt;1,&lt;i&gt;d&lt;/i&gt;&lt;/sub&gt; = &amp;minus;11.45, &lt;i&gt;c&lt;/i&gt;&lt;sub&gt;1,&lt;i&gt;e&lt;/i&gt;&lt;/sub&gt; = &amp;minus;13.66, &lt;i&gt;c&lt;/i&gt;&lt;sub&gt;2,&lt;i&gt;d&lt;/i&gt;&lt;/sub&gt; = 0, &lt;i&gt;c&lt;/i&gt;&lt;sub&gt;2,&lt;i&gt;e&lt;/i&gt;&lt;/sub&gt; = 0, &lt;i&gt;c&lt;/i&gt;&lt;sub&gt;3,&lt;i&gt;d&lt;/i&gt;&lt;/sub&gt; = 57.99, &lt;i&gt;c&lt;/i&gt;&lt;sub&gt;3,&lt;i&gt;e&lt;/i&gt;&lt;/sub&gt; = -83.80, &lt;i&gt;c&lt;/i&gt;&lt;sub&gt;4,&lt;i&gt;d&lt;/i&gt;&lt;/sub&gt; = &amp;minus;106.80, and &lt;i&gt;c&lt;/i&gt;&lt;sub&gt;4,&lt;i&gt;e&lt;/i&gt;&lt;/sub&gt; = 0. The molecular description that is thermodynamically implied by these strongly sloped DRH(&lt;i&gt;&amp;varepsilon;&lt;/i&gt;) and ERH(&lt;i&gt;&amp;varepsilon;&lt;/i&gt;) curves is that the organic isoprene photo-oxidation products, the inorganic ammonium sulfate, and water form a miscible liquid phase even at low relative humidity. This phase miscibility is in contrast to the liquid-liquid separation that occurs for some other types of secondary organic material. These differences in liquid-liquid separation are consistent with a prediction recently presented in the literature that the bifurcation between liquid-liquid phase separation versus mixing depends on the oxygen-to-carbon ratio of the organic material. The conclusions are that the influence of secondary organic material on the hygroscopic properties of ammonium sulfate varies with organic composition and that the degree of oxygenation of the organic material, which is a measurable characteristic of complex organic materials, is an important variable influencing the hygroscopic properties of mixed organic-inorganic particles

Mechanical Behavior of Mushy Zone in DC casting using a Viscoplastic Material Model

Direct Chill (DC) casting is a semi-continuous metal manufacturing process for producing non-ferrous alloys such as aluminum and magnesium. During the solidification of the alloy, there exists a semi-solid state of material known as mushy zone which is more prone to hot tearing. Precise modeling of hot tearing is the most challenging task due to the interaction of many physical fields. The deformation of the partially coherent solid strongly influences the hot cracking. This work focuses on the material behavior of the mushy zone which is the prerequisite for the development of hot tearing criteria. The rate-dependent nature plays a crucial role at higher temperatures. Therefore, the viscoplastic material models with temperature-dependent coefficients are implemented for the characterization of the mushy zone. The numerical integration of the constitute equations are explained in detail. The liquid flow is neglected, and the momentum and energy equations are solved for the mushy and solid phases. With the help of a viscoplastic material models, the stress and strain evolution in the mushy zone is captured. It is found that the state of stress in mushy region is tensile in nature which is a favorable situation for the hot cracks. The influence of the casting speed and secondary cooling on the mushy stress state are analyzed in detail

Measurements of few-mode fiber photonic lanterns in emulated atmospheric conditions for a low earth orbit space to ground optical communication receiver application

Photonic lanterns are being evaluated as a component of a scalable photon counting real-time optical ground receiver for space-to-ground photon-starved communication applications. The function of the lantern as a component of a receiver is to efficiently couple and deliver light from the atmospherically distorted focal spot formed behind a telescope to multiple small-core fiber-coupled single-element super-conducting nanowire detectors. This architecture solution is being compared to a multimode fiber coupled to a multi-element detector array. This paper presents a set of measurements that begins this comparison. This first set of measurements are a comparison of the throughput coupling loss at emulated atmospheric conditions for the case of a 60 cm diameter telescope receiving light from a low earth orbit satellite. The atmospheric conditions are numerically simulated at a range of turbulence levels using a beam propagation method and are physically emulated with a spatial light modulator. The results show that for the same number of output legs as the single-mode fiber lantern, the few-mode fiber lantern increases the power throughput up to 3.92 dB at the worst emulated atmospheric conditions tested of D/r(sub 0)=8.6. Furthermore, the coupling loss of the few-mode fiber lantern approaches the capability of a 30 micron graded index multimode fiber chosen for coupling to a 16 element detector array