Expression, Purification, Crystallization and Preliminary X-Ray Analysis of \u3cem\u3ePseudomonas aeuginosa\u3c/em\u3e AlgX

AlgX is a periplasmic protein required for the production of the exopolysaccharide alginate in Pseudomonas sp. and Azotobacter vinelandii. AlgX has been overexpressed and purified and diffraction-quality crystals have been grown using iterative seeding and the hanging-drop vapor-diffusion method. The crystals grew as flat plates with unit-cell parameters a=46.4, b=120.6, c=86.9Å, β=95.7°. The cyrstals exhibited the symmetry of space group P21 and diffracted to a minimimum d-spacing of 2.1Å. On the basis of the Matthews coefficient (VM=2.25Å3 Da-1), two molecules were estimated to be present in the asymmetric unit

High Sensitivity Search for v_e’s from the Sun and Other Sources at KamLAND

Data corresponding to a KamLAND detector exposure of 0.28 kton yr has been used to search for ν̅ _e’s in the energy range 8.3 < E_(ν̅e) < 14.8  MeV. No candidates were found for an expected background of 1.1±0.4 events. This result can be used to obtain a limit on ν̅_e fluxes of any origin. Assuming that all ν̅_e flux has its origin in the Sun and has the characteristic ^8B solar ν_e energy spectrum, we obtain an upper limit of 3.7×10^2  cm^(-2) ^(s-1) (90% C.L.) on the ν̅_e flux. We interpret this limit, corresponding to 2.8×10^(-4) of the standard solar model ^8B ν_e flux, in the framework of spin-flavor precession and neutrino decay models

Charge asymmetry in hadroproduction of heavy quarks

A sizeable difference in the differential production cross section of top and antitop quarks, respectively, is predicted for hadronically produced heavy quarks. It is of order $\alpha_s$ and arises from the interference between charge odd and even amplitudes respectively. For the TEVATRON it amounts to approximately 5-10% in the region where the cross section is large and could therefore be measured in the next round of experiments. At the LHC the asymmetry can be studied by selecting appropriately chosen kinematical regions.Comment: LaTeX, 5pp, 5 figures, uses revtex. The complete paper, including figures, is also available via anonymous ftp at ftp://ttpux2.physik.uni-karlsruhe.de/ , or via www at http://www-ttp.physik.uni-karlsruhe.de/cgi-bin/preprints/ Final version as published in Phys.Rev.Let

Considerations for the measurement of core, skin and mean body temperatures

Despite previous reviews and commentaries, significant misconceptions remain concerning deep-body (core) and skin temperature measurement in humans. Therefore, the authors have assembled the pertinent Laws of Thermodynamics and other first principles that govern physical and physiological heat exchanges. The resulting review is aimed at providing theoretical and empirical justifications for collecting and interpreting these data. The primary emphasis is upon deep-body temperatures, with discussions of intramuscular, subcutaneous, transcutaneous and skin temperatures included. These are all turnover indices resulting from variations in local metabolism, tissue conduction and blood flow. Consequently, inter-site differences and similarities may have no mechanistic relationship unless those sites have similar metabolic rates, are in close proximity and are perfused by the same blood vessels. Therefore, it is proposed that a gold standard deep-body temperature does not exist. Instead, the validity of each measurement must be evaluated relative to one\u27s research objectives, whilst satisfying equilibration and positioning requirements. When using thermometric computations of heat storage, the establishment of steady-state conditions is essential, but for clinically relevant states, targeted temperature monitoring becomes paramount. However, when investigating temperature regulation, the response characteristics of each temperature measurement must match the forcing function applied during experimentation. Thus, during dynamic phases, deep-body temperatures must be measured from sites that track temperature changes in the central blood volume

Calibrating the DARHT Electron Spectrometer with Negative Ions

Negative ions of hydrogen and oxygen have been used to calibrate the DARHT electron spectrometer over the momentum range of 2 to 20 MeV/c. The calibration was performed on September 1, 3, and 8, 2004, and it is good to 0.5% absolute, provided that instrument alignment is carefully controlled. The momentum in MeV/c as a function of magnetic field (B in Gauss) and position in the detector plane (X in mm) is: P = (B-6.28)/(108.404-0.1935*X

Investigation of the Building M6-794 Roofing Fatality, Type A Mishap

The Building M6-794 Roofing Fatality Mishap Investigation Board (Board) was commissioned to gather information; analyze the facts; identify the proximate causes, root causes, and contributing factors relating to the mishap; and recommend appropriate actions to prevent a similar mishap from occurring in the future. During the investigation of this mishap, the Board also examined the fall protection policies of other NASA Centers and operating locations to gain an understanding of how those entities conduct fall protection, as well as the degree to which fall protection is standardized across the Agency

A proposed measurement of the ß asymmetry in neutron decay with the Los Alamos Ultra-Cold Neutron Source

This article reviews the status of an experiment to study the neutron spin-electron angular correlation with the Los Alamos Ultra-Cold Neutron (UCN) source. The experiment will generate UCNs from a novel solid deuterium, spallation source, and polarize them in a solenoid magnetic field. The experiment spectrometer will consist of a neutron decay region in a solenoid magnetic field combined with several different detector possibilities. An electron beam and a magnetic spectrometer will provide a precise, absolute calibration for these detectors. An A-correlation measurement with a relative precision of 0.2% is expected by the end of 2002

Two-electron quantum dots as scalable qubits

We show that two electrons confined in a square semiconductor quantum dot have two isolated low-lying energy eigenstates, which have the potential to form the basis of scalable computing elements (qubits). Initialisation, one-qubit and two-qubit universal gates, and readout are performed using electrostatic gates and magnetic fields. Two-qubit transformations are performed via the Coulomb interaction between electrons on adjacent dots. Choice of initial states and subsequent asymmetric tuning of the tunnelling energy parameters on adjacent dots control the effect of this interaction.Comment: Revised version, accepted by PR