2,513 research outputs found
Ab initio Modelling of the Early Stages of Precipitation in Al-6000 Alloys
Age hardening induced by the formation of (semi)-coherent precipitate phases
is crucial for the processing and final properties of the widely used Al-6000
alloys. Early stages of precipitation are particularly important from the
fundamental and technological side, but are still far from being fully
understood. Here, an analysis of the energetics of nanometric precipitates of
the meta-stable phases is performed, identifying the bulk, elastic
strain and interface energies that contribute to the stability of a nucleating
cluster. Results show that needle-shape precipitates are unstable to growth
even at the smallest size formula unit, i.e. there is no energy
barrier to growth. The small differences between different compositions points
toward the need for the study of possible precipitate/matrix interface
reconstruction. A classical semi-quantitative nucleation theory approach
including elastic strain energy captures the trends in precipitate energy
versus size and composition. This validates the use of mesoscale models to
assess stability and interactions of precipitates. Studies of smaller 3d
clusters also show stability relative to the solid solution state, indicating
that the early stages of precipitation may be diffusion-limited. Overall, these
results demonstrate the important interplay among composition-dependent bulk,
interface, and elastic strain energies in determining nanoscale precipitate
stability and growth
ON A COLLECTION OF BIRDS FROM ENGGANO
abstract not availabl
Large violation of Bell inequalities with low entanglement
In this paper we obtain violations of general bipartite Bell inequalities of
order with inputs, outputs and
-dimensional Hilbert spaces. Moreover, we construct explicitly, up to a
random choice of signs, all the elements involved in such violations: the
coefficients of the Bell inequalities, POVMs measurements and quantum states.
Analyzing this construction we find that, even though entanglement is necessary
to obtain violation of Bell inequalities, the Entropy of entanglement of the
underlying state is essentially irrelevant in obtaining large violation. We
also indicate why the maximally entangled state is a rather poor candidate in
producing large violations with arbitrary coefficients. However, we also show
that for Bell inequalities with positive coefficients (in particular, games)
the maximally entangled state achieves the largest violation up to a
logarithmic factor.Comment: Reference [16] added. Some typos correcte
Regulation of the F0F1-ATP synthase: The conformation of subunit ε might be determined by directionality of subunit γ rotation
AbstractF0F1-ATP synthase couples ATP synthesis/hydrolysis with transmembrane proton transport. The catalytic mechanism involves rotation of the γεc∼10-subunits complex relative to the rest of the enzyme.In the absence of protonmotive force the enzyme is inactivated by the tight binding of MgADP. Subunit ε also modulates the activity: its conformation can change from a contracted to extended form with C-terminus stretched towards F1. The latter form ihnibits ATP hydrolysis (but not synthesis).We propose that the directionality of the coiled-coil subunit γ rotation determines whether subunit ε is in contracted or extended form. Block of rotation by MgADP presumably induces the extended conformation of subunit ε. This conformation might serve as a safety lock, stabilizing the ADP-inhibited state upon de-energization and preventing spontaneous re-activation and wasteful ATP hydrolysis. The hypothesis merges the known regulatory effects of ADP, protonmotive force and conformational changes of subunit ε into a consistent picture
Expansion of neopterin and beta2-microglobulin in cerebrospinal fluid reaches maximum levels early and late in the course of human immunodeficiency virus infection
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Thermal coal drying with the high volatile matter output
Наведено аналіз сучасних технологій сушіння вугілля з високим вмістом летких. Промислове застосування набули парові сушарки з киплячим шаром продуктивністю 55 т/год, в яких теплоносієм є інертний азот, а необхідне тепло отримують за рахунок відхідних газів газифікатора, при цьому теплопередача здійснюється за допомогою гарячої води.Приведен анализ современных технологий сушки углей с высоким содержанием летучих. Промышленное применение получили паровые сушилки с кипящим слоем производительностью 55 т/ч, в которых теплоносителем служит инертный азот, а необходимое тепло получают за счет отходящих газов газификатора, при этом теплопередача осуществляется посредством горячей воды.An analysis of modern technologies of drying of coals with high content of volatile. Industrial applications received steam dryer with a fluidized bed with capacity of 55 tons/h, in which the coolant is inert nitrogen, and the necessary heat is generated by waste gases of the gasifier, the heat transfer is carried out by means of hot water
From joint convexity of quantum relative entropy to a concavity theorem of Lieb
This paper provides a succinct proof of a 1973 theorem of Lieb that establishes the concavity of a certain trace function. The development relies on a deep result from quantum information theory, the joint convexity of quantum relative entropy, as well as a recent argument due to Carlen and Lieb
Optical diode based on the chirality of guided photons
Photons are nonchiral particles: their handedness can be both left and right.
However, when light is transversely confined, it can locally exhibit a
transverse spin whose orientation is fixed by the propagation direction of the
photons. Confined photons thus have chiral character. Here, we employ this to
demonstrate nonreciprocal transmission of light at the single-photon level
through a silica nanofibre in two experimental schemes. We either use an
ensemble of spin-polarised atoms that is weakly coupled to the nanofibre-guided
mode or a single spin-polarised atom strongly coupled to the nanofibre via a
whispering-gallery-mode resonator. We simultaneously achieve high optical
isolation and high forward transmission. Both are controlled by the internal
atomic state. The resulting optical diode is the first example of a new class
of nonreciprocal nanophotonic devices which exploit the chirality of confined
photons and which are, in principle, suitable for quantum information
processing and future quantum optical networks
Development of a German version of the Oswestry Disability Index. Part 1: cross-cultural adaptation, reliability, and validity
Patient-orientated assessment methods are of paramount importance in the evaluation of treatment outcome. The Oswestry Disability Index (ODI) is one of the condition-specific questionnaires recommended for use with back pain patients. To date, no German version has been published in the peer-reviewed literature. A cross-cultural adaptation of the ODI for the German language was carried out, according to established guidelines. One hundred patients with chronic low-back pain (35 conservative, 65 surgical) completed a questionnaire booklet containing the newly translated ODI, along with a 0-10 pain visual analogue scale (VAS), the Roland Morris Disability Questionnaire, and Likert scales for disability, medication intake and pain frequency [to assess ODI's construct (convergent) validity]. Thirty-nine of these patients completed a second questionnaire within 2weeks (to assess test-retest reliability). The intraclass correlation coefficient for the test-retest reliability of the questionnaire was 0.96. In test-retest, 74% of the individual questions were answered identically, and 21% just one grade higher or lower. The standard error of measurement (SEM) was 3.4, giving a "minimum detectable change” (MDC95%) for the ODI of approximately 9 points, i.e. the minimum change in an individual's score required to be considered "real change” (with 95% confidence) over and above measurement error. The ODI scores correlated with VAS pain intensity (r=0.78, P<0.001) and Roland Morris scores (r=0.80, P<0.001). The mean baseline ODI scores differed significantly between the surgical and conservative patients (P<0.001), and between the different categories of the Likert scales for disability, medication use and pain frequency (in each case P<0.001). Our German version of the Oswestry questionnaire is reliable and valid, and shows psychometric characteristics as good as, if not better than, the original English version. It should represent a valuable tool for use in future patient-orientated outcome studies in German-speaking land
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