2,474 research outputs found
{Tc(NO)(Cp)(PPh3)}+ – a novel technetium(I) core
Reactions between [TcI(NO)X2(PPh3)2(CH3CN)] complexes (X = Cl, Br) and KCp
form the pseudotetrahedral organotechnetium compounds [TcI(NO)(Cp)(PPh3)X].
The halide ligands can readily be replaced by other halides or organometallic
ligands giving access to a novel family of technetium(I) compounds with the
robust {Tc(NO)(Cp)(PPh3)}+ core
D-Foam Phenomenology: Dark Energy, the Velocity of Light and a Possible D-Void
In a D-brane model of space-time foam, there are contributions to the dark
energy that depend on the D-brane velocities and on the density of D-particle
defects. The latter may also reduce the speeds of photons linearly with their
energies, establishing a phenomenological connection with astrophysical probes
of the universality of the velocity of light. Specifically, the cosmological
dark energy density measured at the present epoch may be linked to the apparent
retardation of energetic photons propagating from nearby AGNs. However, this
nascent field of `D-foam phenomenology' may be complicated by a dependence of
the D-particle density on the cosmological epoch. A reduced density of
D-particles at redshifts z ~ 1 - a `D-void' - would increase the dark energy
while suppressing the vacuum refractive index, and thereby might reconcile the
AGN measurements with the relatively small retardation seen for the energetic
photons propagating from GRB 090510, as measured by the Fermi satellite.Comment: 10 pages, 3 figure
Interactive Learning-Based Realizability for Heyting Arithmetic with EM1
We apply to the semantics of Arithmetic the idea of ``finite approximation''
used to provide computational interpretations of Herbrand's Theorem, and we
interpret classical proofs as constructive proofs (with constructive rules for
) over a suitable structure \StructureN for the language of
natural numbers and maps of G\"odel's system \SystemT. We introduce a new
Realizability semantics we call ``Interactive learning-based Realizability'',
for Heyting Arithmetic plus \EM_1 (Excluded middle axiom restricted to
formulas). Individuals of \StructureN evolve with time, and
realizers may ``interact'' with them, by influencing their evolution. We build
our semantics over Avigad's fixed point result, but the same semantics may be
defined over different constructive interpretations of classical arithmetic
(Berardi and de' Liguoro use continuations). Our notion of realizability
extends intuitionistic realizability and differs from it only in the atomic
case: we interpret atomic realizers as ``learning agents''
Statistical learning and big data applications
The amount of data generated in the field of laboratory medicine has grown to an extent that conventional laboratory information systems (LISs) are struggling to manage and analyze this complex, entangled information (“Big Data”). Statistical learning, a generalized framework from machine learning (ML) and artificial intelligence (AI) is predestined for processing “Big Data” and holds the potential to revolutionize the field of laboratory medicine. Personalized medicine may in particular benefit from AI-based systems, especially when coupled with readily available wearables and smartphones which can collect health data from individual patients and offer new, cost-effective access routes to healthcare for patients worldwide. The amount of personal data collected, however, also raises concerns about patient-privacy and calls for clear ethical guidelines for “Big Data” research, including rigorous quality checks of data and algorithms to eliminate underlying bias and enable transparency. Likewise, novel federated privacy-preserving data processing approaches may reduce the need for centralized data storage. Generative AI-systems including large language models such as ChatGPT currently enter the stage to reshape clinical research, clinical decision-support systems, and healthcare delivery. In our opinion, AI-based systems have a tremendous potential to transform laboratory medicine, however, their opportunities should be weighed against the risks carefully. Despite all enthusiasm, we advocate for stringent added-value assessments, just as for any new drug or treatment. Human experts should carefully validate AI-based systems, including patient-privacy protection, to ensure quality, transparency, and public acceptance. In this opinion paper, data prerequisites, recent developments, chances, and limitations of statistical learning approaches are highlighted
Radial and elliptic flow at RHIC: further predictions
Using a hydrodynamic model, we predict the transverse momentum dependence of
the spectra and the elliptic flow for different hadrons in Au+Au collisions at
sqrt(s) = 130 A GeV. The dependence of the differential and p_t-integrated
elliptic flow on the hadron mass, equation of state and freeze-out temperature
is studied both numerically and analytically.Comment: 6 pages incl. 7 figures; added v2 for phi mesons in Table 1, plus
some related explanatory text. This version to appear in Physics Letters
Ixodes ricinus spirochete and European erythema chronicum migrans disease.
From three endemic locations of erythema chronicum migrans disease in North Rhine-Westphalia, Germany, we recovered 19 isolates of a spirochete from Ixodes ricinus ticks. The infection rate in adult ticks was 16 percent. The isolated spirochete is immunologically related to the Ixodes dammini spirochete, Borrelia duttoni, and Treponema pallidum. Using indirect immunofluorescence, the sera of 90 patients with erythema chronicum migrans disease showed antibody titers against the isolated spirochete, which correlated with the clinical course. Similarly, antibodies were demonstrated in the sera of 21 patients with acrodermatitis chronica atrophicans. These results suggest an etiologic role for the Ixodes ricinus spriochete in European erythema chronicum migrans disease
Longitudinal validity of spirometers--a challenge in longitudinal studies.
Pulmonary function testing (PFT) in longitudinal studies involves the repeated use of spirometers over long time periods. We assess the comparability of PFT results taken under biologic field conditions using thirteen certified devices of various technology and age. Comparability of measurements across devices and over time is relevant both in clinical and epidemiological research.
Forced Vital Capacity (FVC), Forced Expiratory Volume in the first second (FEV1) and Forced Expiratory Flow 50% (FEF50) were compared before and after the data collection of the Swiss Study on Air Pollution and Lung Diseases in Adults (SAPALDIA) and the European Community Respiratory Health Survey (ECRHS) cohort studies. Three test series were conducted with 46, 50 and 56 volunteers using various combinations of spirometers to compare the eight flow-sensing spirometers (Sensormedics 2200) used in the SAPALDIA cross-sectional and follow-up, two new flow-sensing instruments (Sensormedics Vmax) and three volume displacement spirometers (two Biomedin/Baires and one Sensormedics 2400).
The initial comparison (1999/2000) of eight Sensormedics 2200 and the follow-up comparison (2003) of the same devices revealed a maximal variation of up to 2.6% for FVC, 2.4% for FEV1 and 2.8% for FEF50 across devices with no indication of systematic differences between spirometers. Results were also reproducible between Biomedin, Sensormedics 2200 and 2400. The new generation of Sensormedics (Vmax) gave systematically lower results.
The study demonstrates the need to conduct spirometer comparison tests with humans. For follow-up studies we strongly recommend the use of the same spirometers
High Azimuthal Asymmetry in Non-central A+A at RHIC
The high GeV azimuthal asymmetry, , in
non-central nuclear collisions at RHIC is shown to be a sensitive measure of
the initial parton density distribution of the produced quark-gluon plasma. A
generalization of the Gyulassy-Levai-Vitev (GLV) non-abelian energy loss
formalism including Bjorken 1+1D expansion as well as important kinematic
constraints is used.Comment: 4 pages, Revtex, bbox.sty, 4 eps figures, references added, minor
corrections, Phys.Rev.Lett versio
Resource Competition on Integral Polymatroids
We study competitive resource allocation problems in which players distribute
their demands integrally on a set of resources subject to player-specific
submodular capacity constraints. Each player has to pay for each unit of demand
a cost that is a nondecreasing and convex function of the total allocation of
that resource. This general model of resource allocation generalizes both
singleton congestion games with integer-splittable demands and matroid
congestion games with player-specific costs. As our main result, we show that
in such general resource allocation problems a pure Nash equilibrium is
guaranteed to exist by giving a pseudo-polynomial algorithm computing a pure
Nash equilibrium.Comment: 17 page
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