Magnetic polarizability of hadrons from lattice QCD

We extract the magnetic polarizability from the quadratic response of a hadron's mass shift in progressively small static magnetic fields. The calculation is done on a 24x12x12x24 lattice at a = 0.17 fm with an improved gauge action and the clover quark action. The results are compared to those from experiments and models where available.Comment: 3 pages, 3 figures, contribution to Lattice 2002 (spectrum

Evaluating the capabilities and uncertainties of droplet measurements for the fog droplet spectrometer (FM-100)

Droplet size spectra measurements are crucial to obtain a quantitative microphysical description of clouds and fog. However, cloud droplet size measurements are subject to various uncertainties. This work focuses on the error analysis of two key measurement uncertainties arising during cloud droplet size measurements with a conventional droplet size spectrometer (FM-100): first, we addressed the precision with which droplets can be sized with the FM-100 on the basis of the Mie theory. We deduced error assumptions and proposed a new method on how to correct measured size distributions for these errors by redistributing the measured droplet size distribution using a stochastic approach. Second, based on a literature study, we summarized corrections for particle losses during sampling with the FM-100. We applied both corrections to cloud droplet size spectra measured at the high alpine site Jungfraujoch for a temperature range from 0 °C to 11 °C. We showed that Mie scattering led to spikes in the droplet size distributions using the default sizing procedure, while the new stochastic approach reproduced the ambient size distribution adequately. A detailed analysis of the FM-100 sampling efficiency revealed that particle losses were typically below 10% for droplet diameters up to 10 μm. For larger droplets, particle losses can increase up to 90% for the largest droplets of 50 μm at ambient wind speeds below 4.4 m s<sup>−1</sup> and even to >90% for larger angles between the instrument orientation and the wind vector (sampling angle) at higher wind speeds. Comparisons of the FM-100 to other reference instruments revealed that the total liquid water content (LWC) measured by the FM-100 was more sensitive to particle losses than to re-sizing based on Mie scattering, while the total number concentration was only marginally influenced by particle losses. Consequently, for further LWC measurements with the FM-100 we strongly recommend to consider (1) the error arising due to Mie scattering, and (2) the particle losses, especially for larger droplets depending on the set-up and wind conditions

Hydrogen-induced ferromagnetism in ZnO single crystals investigated by Magnetotransport

We investigated the electrical and magnetic properties of low-energy hydrogen-implanted ZnO single crystals with hydrogen concentrations up to 3 at.% in the first 20 nm surface layer between 10 K and 300 K. All samples showed clear ferromagnetic hysteresis loops at 300 K with a saturation magnetization up to 4 emu/g. The measured anomalous Hall effect agrees with the hysteresis loops measured by superconducting quantum interferometer device magnetometry. All the H-treated ZnO crystals exhibited a negative magnetoresistance up to the room temperature. The relative magnitude of the anisotropic magnetoresistance reaches 0.4 % at 250 K and 2 % at 10 K, exhibiting an anomalous, non-monotonous behavior and a change of sign below 100 K. All the experimental data indicate that hydrogen atoms alone in a few percent range trigger a magnetic order in a ZnO crystalline state. Hydrogen implantation turns out to be a simpler and effective method to generate a magnetic order in ZnO, which provides interesting possibilities for future applications due to the strong reduction of the electrical resistance

Probing IMF using nanodust measurements from inside Saturn's magnetosphere

We present a new concept of monitoring the interplanetary magnetic field (IMF) by using in situ measurements of nanodust stream particles in Saturn's magnetosphere. We show that the nanodust detection pattern obtained inside the magnetosphere resembles those observed in interplanetary space and is associated with the solar wind compression regions. Our dust dynamics model reproduces the observed nanodust dynamical properties as well as the detection pattern, suggesting that the ejected stream particles can reenter Saturn's magnetosphere at certain occasions due to the dynamical influence from the time‐varying IMF. This method provides information on the IMF direction and a rough estimation on the solar wind compression arrival time at Saturn. Such information can be useful for studies related to the solar wind‐magnetosphere interactions, especially when the solar wind parameters are not directly available. Key Points A new method to probe IMF with nanodust measurements inside the magnetosphere Under changing IMF, ejected nanoparticles can re‐enter Saturn‐s magnetosphere IMF direction and solar wind compression arrival time can be derivedPeer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/99078/1/grl50604.pd

Relation of Structure to the Microhardness of Human Dentin

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/66589/2/10.1177_00220345590380032701.pd

Influence of water uptake on the aerosol particle light scattering coefficients of the Central European aerosol

The influence of aerosol water uptake on the aerosol particle light scattering was examined at the regional continental research site Melpitz, Germany. The scattering enhancement factor f(RH), defined as the aerosol particle scattering coefficient at a certain relative humidity (RH) divided by its dry value, was measured using a humidified nephelometer. The chemical composition and other microphysical properties were measured in parallel. f(RH) showed a strong variation, e.g. with values between 1.2 and 3.6 at RH=85% and λ=550 nm. The chemical composition was found to be the main factor determining the magnitude of f(RH), since the magnitude of f(RH) clearly correlated with the inorganic mass fraction measured by an aerosol mass spectrometer (AMS). Hysteresis within the recorded humidograms was observed and explained by long-range transported sea salt. A closure study using Mie theory showed the consistency of the measured parameters

Knockout studies reveal an important role of <i>plasmodium</i> lipoic acid protein ligase a1 for asexual blood stage parasite survival

Lipoic acid (LA) is a dithiol-containing cofactor that is essential for the function of a-keto acid dehydrogenase complexes. LA acts as a reversible acyl group acceptor and 'swinging arm' during acyl-coenzyme A formation. The cofactor is post-translationally attached to the acyl-transferase subunits of the multienzyme complexes through the action of octanoyl (lipoyl): &lt;i&gt;N&lt;/i&gt;-octanoyl (lipoyl) transferase (LipB) or lipoic acid protein ligases (LplA). Remarkably, apicomplexan parasites possess LA biosynthesis as well as scavenging pathways and the two pathways are distributed between mitochondrion and a vestigial organelle, the apicoplast. The apicoplast-specific LipB is dispensable for parasite growth due to functional redundancy of the parasite's lipoic acid/octanoic acid ligases/transferases. In this study, we show that &lt;i&gt;LplA1&lt;/i&gt; plays a pivotal role during the development of the erythrocytic stages of the malaria parasite. Gene disruptions in the human malaria parasite &lt;i&gt;P.falciparum&lt;/i&gt; consistently were unsuccessful while in the rodent malaria model parasite &lt;i&gt;P. berghei&lt;/i&gt; the &lt;i&gt;LplA1&lt;/i&gt; gene locus was targeted by knock-in and knockout constructs. However, the &lt;i&gt;LplA1&lt;/i&gt; &lt;sup&gt;(-)&lt;/sup&gt; mutant could not be cloned suggesting a critical role of LplA1 for asexual parasite growth &lt;i&gt;in vitro&lt;/i&gt; and &lt;i&gt;in vivo&lt;/i&gt;. These experimental genetics data suggest that lipoylation during expansion in red blood cells largely occurs through salvage from the host erythrocytes and subsequent ligation of LA to the target proteins of the malaria parasite

Real and Virtual Compton Scattering: the nucleon polarisabilities

We give an overview of low-energy Compton scattering (gamma^(*) p --> gamma p) with a real or virtual incoming photon. These processes allow the investigation of one of the fundamental properties of the nucleon, i.e. how its internal structure deforms under an applied static electromagnetic field. Our knowledge of nucleon polarisabilities and their generalization to non-zero four-momentum transfer will be reviewed, including the presently ongoing experiments and future perspectives.Comment: 20 pages, 12 figures. Minireview/Proceedings of "Many-Body Structure of Strongly Interacting Systems", Mainz, Germany, Feb. 23-25 2011 . V2: typos corrected. version to appear in EPJ Special Topic

Meson exchange and nucleon polarizabilities in the quark model

Modifications to the nucleon electric polarizability induced by pion and sigma exchange in the q-q potentials are studied by means of sum rule techniques within a non-relativistic quark model. Contributions from meson exchange interactions are found to be small and in general reduce the quark core polarizability for a number of hybrid and one-boson-exchange q-q models. These results can be explained by the constraints that the baryonic spectrum impose on the short range behavior of the mesonic interactions.Comment: 11 pages, 1 figure added, expanded discussio