Protein Mobility in the Cytoplasm of Escherichia coli

The rate of protein diffusion in bacterial cytoplasm may constrain a variety of cellular functions and limit the rates of many biochemical reactions in vivo. In this paper, we report noninvasive measurements of the apparent diffusion coefficient of green fluorescent protein (GFP) in the cytoplasm of Escherichia coli. These measurements were made in two ways: by photobleaching of GFP fluorescence and by photoactivation of a red-emitting fluorescent state of GFP (M. B. Elowitz, M. G. Surette, P. E. Wolf, J. Stock, and S. Leibler, Curr. Biol. 7:809-812, 1997). The apparent diffusion coefficient, Da, of GFP in E. coli DH5alpha was found to be 7.7 ± 2.5 µm^2/s. A 72-kDa fusion protein composed of GFP and a cytoplasmically localized maltose binding protein domain moves more slowly, with Da of 2.5 ± 0.6 µm^2/s. In addition, GFP mobility can depend strongly on at least two factors: first, Da is reduced to 3.6 ± 0.7 µm^2/s at high levels of GFP expression; second, the addition to GFP of a small tag consisting of six histidine residues reduces Da to 4.0 ± 2.0 µm^2/s. Thus, a single effective cytoplasmic viscosity cannot explain all values of Da reported here. These measurements have implications for the understanding of intracellular biochemical networks

Time-dependent Schr\"odinger equations having isomorphic symmetry algebras. I. Classes of interrelated equations

In this paper, we focus on a general class of Schr\"odinger equations that are time-dependent and quadratic in X and P. We transform Schr\"odinger equations in this class, via a class of time-dependent mass equations, to a class of solvable time-dependent oscillator equations. This transformation consists of a unitary transformation and a change in the ``time'' variable. We derive mathematical constraints forthe transformation and introduce two examples.Comment: LaTeX, 18 pages, new format, edite

Liquid segregation parameters from amphibolite dehydration melting experiments

We have experimentally obtained some of the parameters necessary for understanding the segregation of silicate liquid from amphibolite undergoing dehydration melting at 1 GPa and 750–1000°C. The solidus for this calcic amphibolite (68% Mg-Hb, 32% Pl (An_(90))) is <750°C. Amphibolites begin to melt at relatively high temperatures in the garnet-absent field, but the solidus appears to backbend at ∼1 GPa, coincident with the garnet-in boundary. Hornblende breakdown due to garnet formation releases H_2O and causes melting. Thus, in the garnet-present field (≥1 GPa), the amphibolite dehydration melting solidus may be coincident with the H_2O-saturated solidus. Liquid interconnectivity may be achieved at <900°C and <5 vol % liquid, based on both physical and chemical data from solid rock runs. Mass balance calculations from powdered rock runs suggest that small amounts (∼5–15 vol %) of hydrous (≥4 wt % H_2O), low-viscosity (10^3–10^4 Pa s), heavy rare earth element-depleted, felsic liquid may be segregated during amphibolite dehydration melting at ≥875°C. The rapid breakdown of coarse-grained Hb cores may lead to the formation of transient H_2O-saturated liquids with even lower viscosities (∼10^2 Pa s). Although comprising only a small portion of the melting cycle, these H_2O-rich conditions may enhance the segregation of liquid by reduction of liquid viscosities and by mechanical effects on the restite (e.g., increased deformation and liquid fracturing). During anatexis of coarse-grained (natural) rocks, transient conditions may control the initial stages of liquid segregation

Non-disturbing quantum measurements

We consider pairs of quantum observables (POVMs) and analyze the relation between the notions of non-disturbance, joint measurability and commutativity. We specify conditions under which these properties coincide or differ---depending for instance on the interplay between the number of outcomes and the Hilbert space dimension or on algebraic properties of the effect operators. We also show that (non-)disturbance is in general not a symmetric relation and that it can be decided and quantified by means of a semidefinite program.Comment: Minor corrections in v

Effects of Heat Treatment of Spinels as Determined by VIS/NIR and Raman Spectroscopy and XRD

Heat treatment is done to improve the color and clarity and, therefore, the value of gemstones. The objectives of this study include observing color and inclusion changes in pink spinels after heat treatment, and analyzing structural changes within differently colored spinels using Raman Spectroscopy and X-ray diffraction with a Paris Edinburgh Press. We expected the heat treatment to yield color changes and fading of small inclusions. Cut and polished spinels were heated to 1400C for 2 days or 850C for 3 days. Future experiments involve 800C, 750C, and 700C all for 1 week, 1500C for 4 days, and 1600C for 12 hours. To determine changes, Vis/NIR spectroscopy data were taken before and after heating. Only non-heat treated spinels were analyzed with the Paris Edinburgh Press; these XRD data show that the spinels with different colors are structurally different from one another. Raman spectroscopy was used in this study to observe structural changes in spinels that were exposed to heat. Six spinels were heated to 850C for 24 hours, six spinels were heated at 1200C for 6 hours, and the last six were heated at 1600C for 6 hours. The Raman spectroscopy data show that the six spinels exposed to 850C for 24 hours did not change structurally, but the 12 spinels exposed to 1200C or 1600C for six hours did change structurally

Area laws in quantum systems: mutual information and correlations

The holographic principle states that on a fundamental level the information content of a region should depend on its surface area rather than on its volume. This counterintuitive idea which has its roots in the nonextensive nature of black-hole entropy serves as a guiding principle in the search for the fundamental laws of Planck-scale physics. In this paper we show that a similar phenomenon emerges from the established laws of classical and quantum physics: the information contained in part of a system in thermal equilibrium obeys an area law. While the maximal information per unit area depends classically only on the number of microscopic degrees of freedom, it may diverge as the inverse temperature in quantum systems. A rigorous relation between area laws and correlations is established and their explicit behavior is revealed for a large class of quantum many-body states beyond equilibrium systems.Comment: 5 pages, 2 figures, published version with appendi

Geochemical Analysis and Heat-Treatment of Natural Sapphires from Madagascar and Tanzania in Oxidizing and Reducing Conditions

Natural or synthetic sapphires can be heat-treated to improve the clarity by removing “silk” (inclusions) and to change color by introducing color-inducing elements (i.e., chromophores) into the lattice structure or changing their valency. Due to these reasons, sapphires can be heat-treated to increase their monetary value. Twenty natural blue (C1), 20 green (C2), and 20 clear (C3) sapphires from Madagascar and Tanzania were heat-treated in a muffle furnace in oxidizing and reducing conditions, from 1200 to 1600℃, for 10-hour soak time. In total, 5 experiments were conducted in which soak time remained constant: experiment 1 was performed at 1200℃, exp. 2 at 1300℃, exp. 3 at 1400℃, exp. 4 at 1500℃, and exp. 5 at 1600℃. Each experiment contained 4 sapphires from C1, C2, and C3 respectively, and half of the sapphires were exposed to oxidizing conditions, while the other half to reducing conditions. To achieve reducing conditions, graphite slabs were used to create the CCO buffer; the oxidizing conditions were achieved simply with air. The clear (C3) sapphires remained clear under both conditions from 1200 to 1500℃ exclusively and up to 1600℃ in oxidizing conditions. The blue (C1) sapphires either underwent no change of color or became lighter with increasing temperature and some received a yellowing effect resulting in green in oxidizing conditions. In reducing conditions, the blue (C1) sapphires became darker in color, especially from 1400℃ and up. Green/blue (C2) sapphires became lighter and increased the green intensity from 1200 to 1400℃ exclusively and up to 1600℃ in oxidizing conditions. Starting at 1400℃ heat-treatment of the stones in reducing conditions turned almost all of the samples grey/black. Electron microprobe analyses were used to determine concentrations of chromophores at minor and trace element concentrations, including: Ca, Ti, Zn, Mg, Si, Ga, Fe, Mn, and Cr to evaluate the geochemical effects of heat-treating sapphires. C1 sapphires contained the highest amount of Ti and Fe (Ti \u3e 100ppm, Fe 8000-10000 ppm), C2 sapphires contained much less Ti but the same amount of Fe (Ti 40-50ppm) and C3 samples contained the same amount of Ti as C2 but the least amount of Fe (Fe 400-700 ppm)

Nephron-Sparing Diagnosis and Management of Renal Keratinizing Desquamative Squamous Metaplasia

Background and Purpose: Keratinizing desquamative squamous metaplasia (KDSM) of the upper urinary tract is a rare condition for which there is no defined management plan. A condition historically treated with extirpative surgery, conservative management would be preferable, because this is almost certainly a benign condition. We report the favorable clinical course of two cases of renal KDSM diagnosed and managed with a nephron-sparing approach, relying on ureteroscopy and serial imaging. Patients and Methods: Retrospective chart review was performed to obtain history, physical examination results, radiographic imaging, and diagnostic procedures. Results: Both patients were referred to our institution for evaluation of complex cystic renal masses. Both reported passing flaky material in their urine. Flexible ureteroscopy revealed waxy sediment in the collecting system, which broke up easily with manipulation and proved to be squamous keratin debris on cytologic and histologic examination. In 1 patient, we obtained a percutaneous needle biopsy as well, which revealed benign keratinizing squamous epithelium. All findings were consistent with KDSM. Each patient has since been followed conservatively with CT. In 1 case, there has been slight growth of the mass but no worrisome changes after 42 months. In the other case, there were several new renal collecting system filling defects on CT 17 months after diagnosis. Another ureteroscopy revealed the same findings as the original, with the addition of keratin debris draining out of the lesion into the rest of the kidney. Conclusions: Our two cases of KDSM confirm the feasibility of nephron-sparing management using a combination of diagnostic ureteroscopy and imaging surveillance. The duration of follow-up without adverse events suggests that the finding of renal KDSM is not necessarily an indication for extirpative surgery, and that conservative management is an appropriate option.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/78150/1/end.2008.0501.pd

Stochastic exclusion processes versus coherent transport

Stochastic exclusion processes play an integral role in the physics of non-equilibrium statistical mechanics. These models are Markovian processes, described by a classical master equation. In this paper a quantum mechanical version of a stochastic hopping process in one dimension is formulated in terms of a quantum master equation. This allows the investigation of coherent and stochastic evolution in the same formal framework. The focus lies on the non-equilibrium steady state. Two stochastic model systems are considered, the totally asymmetric exclusion process and the fully symmetric exclusion process. The steady state transport properties of these models is compared to the case with additional coherent evolution, generated by the $XX$-Hamiltonian