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Travis Peak Formation, East Texas
Sandstone in the Travis Peak (Hosston) Formation has been extensively modified by burial diagenesis. Permeability in much of the formation has been reduced to less than 0.1 md as a result of compaction extensive precipitation of authigenic minerals, and minor pressure solution. Thin zones of higher porosity and permeability occur mainly near the top of the formation: porosity and permeability decrease with depth below the top. The Travis Peak Formation in East Texas is approximately 2,000 ft (600 m) thick; depth to the top of the formation ranges from 5,800 ft (1,770 m) to 9,400 ft (2,870 m). Travis Peak sandstone is fine- to very fine-grained quartzarenite and subarkose having an average composition of Qââ
FâRâ. Plagioclase feldspar is more abundant than orthoclase, and chert and low-rank metamorphic rock fragments are the most common lithic components. The first authigenic cement to precipitate was illite, which coated detrital grains with tangentially oriented crystals. Next, extensive quartz cement, averaging 17% of the rock volume in well-sorted sandstone, occluded much of the primary porosity. Quartz cement is most abundant in the lower Travis Peak, in well-connected sandstone beds that were deposited in braided streams. Oxygen-isotopic composition of quartz overgrowths indicates that they precipitated from meteoric fluids at temperatures of 130° to 165°F (55° to 75°C). These temperatures equate to depths of 3,000 to 5,000 ft (900 to 1,500 m). Dissolution of orthoclase and albitization of plagioclase followed quartz cementation and occurred prior to mid-Cretaceous movement of the Sabine Uplift. An abrupt loss of orthoclase occurs at 1,200 ft (365 m) below the top of the Travis Peak, and albitization is more extensive deeper in the formation. Illite (a second generation), chlorite, and ankerite precipitated after feldspar diagenesis; these late authigenic phases incorporate ferrous iron released by thermal reduction of iron compounds. Ankerite was derived primarily from early dolomite cement, but it incorporated some light carbon from maturation of organic matter and radiogenic strontium from feldspar dissolution. The oxygen-isotopic composition of pore fluids evolved during ankerite precipitation from -4 o/oo to +3 o/oo (SMOW); +3 o/oo is the present composition of Travis Peak water. Oil migrated into Travis Peak reservoirs about 65 mya from shale in the Bossier Formation. Later deasphalting of the oil filled much of the remaining porosity in some zones near the top of the formation with reservoir bitumen.Geological Science
Achieving minimum-error discrimination of an arbitrary set of laser-light pulses
Laser light is widely used for communication and sensing applications, so the
optimal discrimination of coherent states--the quantum states of light emitted
by a laser--has immense practical importance. However, quantum mechanics
imposes a fundamental limit on how well different coher- ent states can be
distinguished, even with perfect detectors, and limits such discrimination to
have a finite minimum probability of error. While conventional optical
receivers lead to error rates well above this fundamental limit, Dolinar found
an explicit receiver design involving optical feedback and photon counting that
can achieve the minimum probability of error for discriminating any two given
coherent states. The generalization of this construction to larger sets of
coherent states has proven to be challenging, evidencing that there may be a
limitation inherent to a linear-optics-based adaptive measurement strategy. In
this Letter, we show how to achieve optimal discrimination of any set of
coherent states using a resource-efficient quantum computer. Our construction
leverages a recent result on discriminating multi-copy quantum hypotheses
(arXiv:1201.6625) and properties of coherent states. Furthermore, our
construction is reusable, composable, and applicable to designing
quantum-limited processing of coherent-state signals to optimize any metric of
choice. As illustrative examples, we analyze the performance of discriminating
a ternary alphabet, and show how the quantum circuit of a receiver designed to
discriminate a binary alphabet can be reused in discriminating multimode
hypotheses. Finally, we show our result can be used to achieve the quantum
limit on the rate of classical information transmission on a lossy optical
channel, which is known to exceed the Shannon rate of all conventional optical
receivers.Comment: 9 pages, 2 figures; v2 Minor correction
Measurement of teicoplanin by liquid chromatography-tandem mass spectrometry:development of a novel method
Teicoplanin is an antibiotic used for the treatment of endocarditis, osteomyelitis, septic arthritis and methicillin-resistant Staphylococcus aureus. Teicoplanin is emerging as a suitable alternative antibiotic to vancomycin, where their trough serum levels are monitored by immunoassay routinely. This is the first report detailing the development of a liquid chromatography-tandem mass spectrometry (LC-MS/MS) method for measuring teicoplanin in patients' serum
Storing and processing optical information with ultra-slow light in Bose-Einstein condensates
We theoretically explore coherent information transfer between ultra-slow
light pulses and Bose-Einstein condensates (BECs) and find that storing light
pulses in BECs, by switching off the coupling field, allows the coherent
condensate dynamics to process optical information. We develop a formalism,
applicable in both the weak and strong probe regimes, to analyze such
experiments and establish several new results. Investigating examples relevant
to Rb-87 experimental parameters we see a variety of novel two-component BEC
dynamics occur during the storage, including interference fringes, gentle
breathing excitations, and two-component solitons. We find the dynamics when
the levels |F=1, M_F=-1> and |F=2, M_F=+1> are well suited to designing
controlled processing of the information. By switching the coupling field back
on, the processed information is rewritten onto probe pulses which then
propagate out as slow light pulses. We calculate the fidelity of information
transfer between the atomic and light fields upon the switch-on and subsequent
output. The fidelity is affected both by absorption of small length scale
features and absorption of regions of the pulse stored near the condensate
edge. In the strong probe case, we find that when the oscillator strengths for
the two transitions are equal the fidelity is not strongly sensitive to the
probe strength, while when they are unequal the fidelity is worse for stronger
probes. Applications to distant communication between BECs, squeezed light
generation and quantum information are anticipated.Comment: 19 pages, 12 figures, submitted to Phys. Rev.
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