5,216 research outputs found
Review Article of Lawson, Todd. 'The Crucifixion and the Qur’an: A Study in the History of Muslim Thought'
The invisible businessman: Nuclear physics, patenting practices,and trading activities in the 1930s
In the 1930s the production of patents for the protection of intellectual rights became central to the research activities of Enrico Fermi and his group, consistently with a research policy emerging within the Italian Fascist Regime. Behind their work was an international network consisting of businessmen, industrialists, and multinationals who helped them patent their method for the production of artificial radioactive elements and to promote its industrial exploitation. The lack of research funding combined with a more aggressive foreign policy of the regime made it impossible for the group to continue these activities in Rome, and in 1938 the promulgation
of racial laws forced them to migrate abroad
American Society for Echocardiography Software Suite for Verification and
The imminent balloting of the draft DICOM 3.0 module
on ultrasound represents a major step forward in the
progress of digital storage formats for
echocardiography. In this paper, we discuss a software
suite soon to be released into the public domain for
reading, parsing and verifying DICOM 3.0 ultrasonic
objects. The software is designed to allow the user to
verify that a Jle consisting of digital ultrasound data,
claiming DlCOM 3.0 conformance, does in fact adhere
to the standard. A graphical user-interface for the
software suite is also provided, allowing the playback of
cin& mode images in real-time on standard computer
hardware, and across a TCP/IP network
Rapid planetesimal formation in turbulent circumstellar discs
The initial stages of planet formation in circumstellar gas discs proceed via
dust grains that collide and build up larger and larger bodies (Safronov 1969).
How this process continues from metre-sized boulders to kilometre-scale
planetesimals is a major unsolved problem (Dominik et al. 2007): boulders stick
together poorly (Benz 2000), and spiral into the protostar in a few hundred
orbits due to a head wind from the slower rotating gas (Weidenschilling 1977).
Gravitational collapse of the solid component has been suggested to overcome
this barrier (Safronov 1969, Goldreich & Ward 1973, Youdin & Shu 2002). Even
low levels of turbulence, however, inhibit sedimentation of solids to a
sufficiently dense midplane layer (Weidenschilling & Cuzzi 1993, Dominik et al.
2007), but turbulence must be present to explain observed gas accretion in
protostellar discs (Hartmann 1998). Here we report the discovery of efficient
gravitational collapse of boulders in locally overdense regions in the
midplane. The boulders concentrate initially in transient high pressures in the
turbulent gas (Johansen, Klahr, & Henning 2006), and these concentrations are
augmented a further order of magnitude by a streaming instability (Youdin &
Goodman 2005, Johansen, Henning, & Klahr 2006, Johansen & Youdin 2007) driven
by the relative flow of gas and solids. We find that gravitationally bound
clusters form with masses comparable to dwarf planets and containing a
distribution of boulder sizes. Gravitational collapse happens much faster than
radial drift, offering a possible path to planetesimal formation in accreting
circumstellar discs.Comment: To appear in Nature (30 August 2007 issue). 18 pages (in referee
mode), 3 figures. Supplementary Information can be found at 0708.389
Displacements analysis of self-excited vibrations in turning
The actual research deals with determining by a new protocol the necessary
parameters considering a three-dimensional model to simulate in a realistic way
the turning process on machine tool. This paper is dedicated to the
experimental displacements analysis of the block tool / block workpiece with
self-excited vibrations. In connexion with turning process, the self-excited
vibrations domain is obtained starting from spectra of two accelerometers. The
existence of a displacements plane attached to the tool edge point is revealed.
This plane proves to be inclined compared to the machines tool axes. We
establish that the tool tip point describes an ellipse. This ellipse is very
small and can be considered as a small straight line segment for the stable
cutting process (without vibrations). In unstable mode (with vibrations) the
ellipse of displacements is really more visible. A difference in phase occurs
between the tool tip displacements on the radial direction and on the cutting
one. The feed motion direction and the cutting one are almost in phase. The
values of the long and small ellipse axes (and their ratio) shows that these
sizes are increasing with the feed rate value. The axis that goes through the
stiffness center and the tool tip represents the maximum stiffness direction.
The maximum (resp. minimum) stiffness axis of the tool is perpendicular to the
large (resp. small) ellipse displacements axis. FFT analysis of the
accelerometers signals allows to reach several important parameters and
establish coherent correlations between tool tip displacements and the static -
elastic characteristics of the machine tool components tested
A Factorization Law for Entanglement Decay
We present a simple and general factorization law for quantum systems shared
by two parties, which describes the time evolution of entanglement upon passage
of either component through an arbitrary noisy channel. The robustness of
entanglement-based quantum information processing protocols is thus easily and
fully characterized by a single quantity.Comment: 4 pages, 5 figure
Platelet-Induced Clumping of Plasmodium falciparum–Infected Erythrocytes from Malawian Patients with Cerebral Malaria—Possible Modulation In Vivo by Thrombocytopenia
Platelets may play a role in the pathogenesis of human cerebral malaria (CM), and they have been shown to induce clumping of Plasmodium falciparum–parasitized red blood cells (PRBCs) in vitro. Both thrombocytopenia and platelet-inducedPRBCclumping are associated with severe malaria and, especially, withCM.In the present study, we investigated the occurrence of the clumping phenomenon in patients with CM by isolating and coincubating their plasma and PRBCs ex vivo. Malawian children with CM all had low platelet counts, with the degree of thrombocytopenia directly proportional to the density of parasitemia. Plasma samples obtained from these patients subsequently induced weak PRBC clumping. When the assays were repeated, with the plasma platelet concentrations adjusted to within the physiological range considered to be normal, massive clumping occurred. The results of this study suggest that thrombocytopenia may, through reduction of platelet-mediated clumping of PRBCs, provide a protective mechanism for the host during CM
Advancing Tests of Relativistic Gravity via Laser Ranging to Phobos
Phobos Laser Ranging (PLR) is a concept for a space mission designed to
advance tests of relativistic gravity in the solar system. PLR's primary
objective is to measure the curvature of space around the Sun, represented by
the Eddington parameter , with an accuracy of two parts in ,
thereby improving today's best result by two orders of magnitude. Other mission
goals include measurements of the time-rate-of-change of the gravitational
constant, and of the gravitational inverse square law at 1.5 AU
distances--with up to two orders-of-magnitude improvement for each. The science
parameters will be estimated using laser ranging measurements of the distance
between an Earth station and an active laser transponder on Phobos capable of
reaching mm-level range resolution. A transponder on Phobos sending 0.25 mJ, 10
ps pulses at 1 kHz, and receiving asynchronous 1 kHz pulses from earth via a 12
cm aperture will permit links that even at maximum range will exceed a photon
per second. A total measurement precision of 50 ps demands a few hundred
photons to average to 1 mm (3.3 ps) range precision. Existing satellite laser
ranging (SLR) facilities--with appropriate augmentation--may be able to
participate in PLR. Since Phobos' orbital period is about 8 hours, each
observatory is guaranteed visibility of the Phobos instrument every Earth day.
Given the current technology readiness level, PLR could be started in 2011 for
launch in 2016 for 3 years of science operations. We discuss the PLR's science
objectives, instrument, and mission design. We also present the details of
science simulations performed to support the mission's primary objectives.Comment: 25 pages, 10 figures, 9 table
Identification of furfural resistant strains of Saccharomyces cerevisiae and Saccharomyces paradoxus from a collection of environmental and industrial isolates
Background Fermentation of bioethanol using lignocellulosic biomass as a raw material provides a sustainable alternative to current biofuel production methods by utilising waste food streams as raw material. Before lignocellulose can be fermented it requires physical, chemical and enzymatic treatment in order to release monosaccharides, a process that causes the chemical transformation of glucose and xylose into the cyclic aldehydes furfural and hydroxyfurfural. These furan compounds are potent inhibitors of Saccharomyces fermentation, and consequently furfural tolerant strains of Saccharomyces are required for lignocellulosic fermentation. Results This study investigated yeast tolerance to furfural and hydroxyfurfural using a collection of 71 environmental and industrial isolates of the baker’s yeast Saccharomyces cerevisiae and its closest relative Saccharomyces paradoxus. The Saccharomyces strains were initially screened for growth on media containing 100 mM glucose and 1.5 mg ml-1 furfural. Five strains were identified that showed a significant tolerance to growth in the presence of furfural and these were then screened for growth and ethanol production in the presence of increasing amounts (0.1-4 mg ml-1) of furfural. Conclusions Of the five furfural tolerant strains S. cerevisiae NCYC 3451 displayed the greatest furfural resistance, and was able to grow in the presence of up to 3.0 mg ml-1 furfural. Furthermore, ethanol production in this strain did not appear to be inhibited by furfural, with the highest ethanol yield observed at 3.0 mg ml-1 furfural. Although furfural resistance was not found to be a trait specific to any one particular lineage or population, three of the strains were isolated from environments where they might be continually exposed to low levels of furfural through the on-going natural degradation of lignocelluloses, and would therefore develop elevated levels of resistance to these furan compounds. Thus these strains represent good candidates for future studies of genetic variation relevant to understanding and manipulating furfural resistance and in the development of tolerant ethanologenic yeast strains for use in bioethanol production from lignocellulose processing
Two-Loop Soft Corrections and Resummation of the Thrust Distribution in the Dijet Region
The thrust distribution in electron-positron annihilation is a classical
precision QCD observable. Using renormalization group (RG) evolution in Laplace
space, we perform the resummation of logarithmically enhanced corrections in
the dijet limit, to next-to-next-to-leading logarithmic (NNLL)
accuracy. We independently derive the two-loop soft function for the thrust
distribution and extract an analytical expression for the NNLL resummation
coefficient . To combine the resummed expressions with the fixed-order
results, we derive the -matching and -matching of the NNLL
approximation to the fixed-order NNLO distribution.Comment: 50 pages, 12 figures, 1 table. Few minor changes. Version accepted
for publication in JHE
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