Siderocapsa Major-- Fact or Artifact?

The validity of the genus Siderocapsa, a group of unicellular iron-depositing bacteria, has been a subject of debate for many years. Lack of photomicroscopic and cultural studies has kept this group in taxonomic obscurity. Bacteria were collected from the Campus pond, Eastern Illinois University, Charleston, Illinois, by a submerged slide/coverslip technique. These bacteria were identified as Siderocapsa major according to the description of Molisch (1909). Scanning electron microscopy of Siderocapsa major microcolonies has shown cells (0.5 by 1.15 μm), in a clear central well (2-6 μm), surrounded by an amorphous material which accumulates with the age of the colony. Most authors have failed to explain how they have concluded that the material sequestered by Siderocapsa microcolonies is iron and/or manganese. Preliminary work employing the Prussian blue Reaction (and modifications) failed to demonstrate the presence of iron in the capsules around these bacteria. X-ray microanalysis also failed to demonstrate the presence of iron. However significant amounts of manganese were found to be present in the extra-cellular material. Some investigators have suggested that Siderocapsa microcolonies are artifacts and the result of rod-shaped bacteria that have become entrapped in the well of a Sphaerotilus natans holdfast whose filament has become dislodged. Scanning electron microscopy has shown that the size and morphology of the holdfast of Sphaerotilus-Leptothrix members does not correspond to the size of the deposit around the Siderocapsa microcapsule. In addition, statistical analysis has shown a definite developmental pattern relating the total number of cells in the microcapsule to the total amount of material deposited. The author concludes, from material observed here, that the Siderocapsa microcolonies are discretely different entities from members of the Sphaerotilus-Leptothrix group but may be related to other heterotrophic bacteria

Siderocapsa Major-- Fact or Artifact?

The validity of the genus Siderocapsa, a group of unicellular iron-depositing bacteria, has been a subject of debate for many years. Lack of photomicroscopic and cultural studies has kept this group in taxonomic obscurity. Bacteria were collected from the Campus pond, Eastern Illinois University, Charleston, Illinois, by a submerged slide/coverslip technique. These bacteria were identified as Siderocapsa major according to the description of Molisch (1909). Scanning electron microscopy of Siderocapsa major microcolonies has shown cells (0.5 by 1.15 μm), in a clear central well (2-6 μm), surrounded by an amorphous material which accumulates with the age of the colony. Most authors have failed to explain how they have concluded that the material sequestered by Siderocapsa microcolonies is iron and/or manganese. Preliminary work employing the Prussian blue Reaction (and modifications) failed to demonstrate the presence of iron in the capsules around these bacteria. X-ray microanalysis also failed to demonstrate the presence of iron. However significant amounts of manganese were found to be present in the extra-cellular material. Some investigators have suggested that Siderocapsa microcolonies are artifacts and the result of rod-shaped bacteria that have become entrapped in the well of a Sphaerotilus natans holdfast whose filament has become dislodged. Scanning electron microscopy has shown that the size and morphology of the holdfast of Sphaerotilus-Leptothrix members does not correspond to the size of the deposit around the Siderocapsa microcapsule. In addition, statistical analysis has shown a definite developmental pattern relating the total number of cells in the microcapsule to the total amount of material deposited. The author concludes, from material observed here, that the Siderocapsa microcolonies are discretely different entities from members of the Sphaerotilus-Leptothrix group but may be related to other heterotrophic bacteria

Search for Light Gluinos via the Spontaneous Appearance of pi+pi- Pairs with an 800 GeV/c Proton Beam at Fermilab

We searched for the appearance of pi+pi- pairs with invariant mass greater than 648 MeV in a neutral beam. Such an observation could signify the decay of a long-lived light neutral particle. We find no evidence for this decay. Our null result severely constrains the existence of an R0 hadron, which is the lightest bound state of a gluon and a light gluino, and thereby also the possibility of a light gluino. Depending on the photino mass, we exclude the R0 in the mass and lifetime ranges of 1.2 -- 4.6 GeV and 2E-10 -- 7E-4 seconds, respectively. (To Appear in Phys. Rev. Lett.)Comment: Documentstyle aps,epsfig,prl (revtex), 6 pages, 7 figure

Search for the Decay KL→π0μ+μ−K_L \to \pi^0 \mu^+ \mu^-

We report on a search for the decay \klpimumu carried out as a part of the KTeV experiment at Fermilab. This decay is expected to have a significant $CP$ violating contribution and a direct measurement will either support the CKM mechanism for CP violation or point to new physics. Two events were observed in the 1997 data with an expected background of $0.87 \pm 0.15$ events, and we set an upper limit \BR{\klpimumu} $<3.8 \times 10^{-10}$ at the 90% confidence level.Comment: See also "Observation of the Decay $K_L\to \mu^+\mu^- \gamma \gamma$", also by the KTeV collaboratio

Measurement of the Decay KL -> Pi0 Gamma Gamma

We report on a new measurement of the decay KL -> pi0 gamma gamma by the KTeV experiment at Fermilab. We determine the KL -> pi0 gamma gamma branching ratio to be (1.68 +/- 0.07 +/- 0.08)x10**-6. Our data shows the first evidence for a low-mass gamma gamma signal as predicted by recent O(p**6) chiral perturbation calculations that include vector meson exchange contributions. From our data, we extract a value for the effective vector coupling aV = -0.72 +/- 0.05 +/- 0.06.Comment: 5 pages, 4 figure

Observation of the Decay KL→μ+μ−γγK_L\to \mu^+\mu^- \gamma \gamma

We have observed the decay $K_L\to \mu^+\mu^- \gamma \gamma$ at the KTeV experiment at Fermilab. This decay presents a formidable background to the search for new physics in $K_L\to\pi^0\mu^+\mu^-$. The 1997 data yielded a sample of 4 signal events, with an expected background of 0.155 $\pm$ 0.081 events. The branching ratio is ${\mathcal B}(K_L\to \mu^+\mu^- \gamma \gamma$) $= (10.4^{+7.5}_{-5.9} {\rm (stat)} \pm 0.7 {\rm (sys)})\times 10^{-9}$ with $m_{\gamma\gamma} \geq 1 {\rm MeV/c}^2$, consistent with a QED calculation which predicts $(9.1\pm 0.8)\times 10^{-9}$.Comment: See also the paper "Search for the Decay $K_L \to \pi^0 \mu^+ \mu^-$", also by the KTeV collaboratio

Light Gluino Search for Decays Containing pi+pi- or pi0 from a Neutral Hadron Beam at Fermilab

We report on two null searches, one for the spontaneous appearance of $\pi^+\pi^-$ pairs, another for a single $\pi^0$, consistent with the decay of a long-lived neutral particle into hadrons and an unseen neutral particle. For the lowest level gluon-gluino bound state, known as the $R^0$, we exclude the decays $R^0\to \pi^+\pi^-\tilde{\gamma}$ and $R^0\to \pi^0\tilde{\gamma}$ for the masses of $R^0$ and $\tilde{\gamma}$ in the theoretically allowed range. In the most interesting $R^0$ mass range, $\leq 3 GeV/c^2$, we exclude $R^0$ lifetimes from $3\times 10^{-10}$ seconds to as high as $10^{-3}$ seconds, assuming perturbative QCD production for the $R^0$.Comment: 15 pages, 7 figure

Measurement of the branching ratio of pi^0 -> e^+e^- using K_L -> 3 pi^0 decays in flight

The branching ratio of the rare decay pi^0 -> e^+e^- has been measured in E799-II, a rare kaon decay experiment using the KTeV detector at Fermilab. The pi^0's were produced in fully-reconstructed K_L -> 3 pi^0 decays in flight. We observed 275 candidate pi^0 -> e^+e^- events, with an expected background of 21.4 +- 6.2 events which includes the contribution from Dalitz decays. We measured BR(pi^0 -> e^+e^-, x>0.95) = (6.09 +- 0.40 +- 0.24) times 10^{-8}, where the first error is statistical and the second systematic. This result is the first significant observation of the excess rate for this decay above the unitarity lower bound.Comment: New version shortened to PRL length limit. 5 pages, 4 figures. Published in Phys. Rev. Let

Observation of CP Violation in K(L)->pi+pi-e+e- Decays

We report the first observation of a manifestly CP violating effect in the K(L)->pi+pi-e+e- decay mode. A large asymmetry was observed in the distribution of these decays in the CP-odd and T-odd angle phi between the decay planes of the e+e- and pi+pi- pairs in the K(L) center of mass system. After acceptance corrections, the overall asymmetry is found to be 13.6+-2.5 (stat) +-1.2 (syst)%. This is the largest CP-violating effect yet observed integrating over the entire phase space of a mode and the first such effect observed in an angular variable.Comment: 4 pages 4 figures submitted to pr

Search for the Decay K_L -> pi^0 nu nubar using pi^0 -> e^+ e^- gamma

We report on a search for the decay K_L -> pi^0 nu nubar, carried out as a part of E799-II, a rare K_L decay experiment at Fermilab. Within the Standard Model, the K_L -> pi^0 nu nubar decay is dominated by direct CP violating processes, and thus an observation of the decay implies confirmation of direct CP violation. Due to theoretically clean calculations, a measurement of B(K_L -> pi^0 nu nubar) is one of the best ways to determine the CKM parameter eta. No events were observed, and we set an upper limit B(K_L -> pi^0 nu nubar) < 5.9 times 10^-7 at the 90% confidence level.Comment: 5 pages, 4 figure