1,333 research outputs found
Improving Rigid 3-D Calibration for Robotic Surgery
Autonomy is the next frontier of research in robotic surgery and its aim is to improve the quality of surgical procedures in the next future. One fundamental requirement for autonomy is advanced perception capability through vision sensors. In this article, we propose a novel calibration technique for a surgical scenario with a da Vinci Research Kit (dVRK) robot. Camera and robotic arms calibration are necessary to precise position and emulate expert surgeon. The novel calibration technique is tailored for RGB-D cameras. Different tests performed on relevant use cases prove that we significantly improve precision and accuracy with respect to state of the art solutions for similar devices on a surgical-size setups. Moreover, our calibration method can be easily extended to standard surgical endoscope used in real surgical scenario
Theoretical and Experimental Investigation of the Tb3+-Eu3+ Energy Transfer Mechanisms in Cubic A3Tb0.90Eu0.10({PO}4)3 (A = Sr, Ba) Materials
In this study the optical spectroscopy, the excited state dynamics, and in particular the Tb3+ -> Eu3+ energy transfer, have been investigated in detail both from the theoretical and experimental point of view in eulytite double phosphate hosts A(3)Tb(PO4)(3) (A = Sr, Ba) doped with Eu3+. It has been found that the energy transfer is strongly assisted by fast migration in the donor Tb3+ subset. Moreover, the transfer rates and efficiencies depend significantly on the nature of the divalent elements present in the structure and hence on the distances between Tb3+-Eu3+ nearest neighbors. It is shown that the competition between quadrupole-quadrupole and exchange interaction is crucial in accounting for the transfer rates
Anemia and acute coronary syndrome: current perspectives
Reference hemoglobin (Hb) values for the definition of anemia are still largely based on the 1968 WHO Scientific Group report, which established a cutoff value of <13 g/dL for adult men and <12 g/dL for adult nonpregnant women. Subsequent studies identified different normal values according to race and age. Estimated prevalence of anemia on admission in the setting of an acute coronary syndrome (ACS) is between 10% and 43% of the patients depending upon the specific population under investigation. Furthermore, up to 57% of ACS patients may develop hospital-acquired anemia (HAA). Both anemia on admission and HAA are associated with worse short- and long-term mortality, even if different mechanisms contribute to their prognostic impact. Baseline anemia can usually be traced back to preexisting disease that should be specifically investigated and corrected whenever possible. HAA is associated with clinical characteristics, medical therapy and interventional procedures, all eliciting cardiovascular adaptive response that can potentially worsen myocardial ischemia. The intrinsic fragility of anemic patients may limit aggressive medical and interventional therapy due to an increased risk of bleeding, and could independently contribute to worse outcome. However, primary angioplasty for ST elevation ACS should not be delayed because of preexisting (and often not diagnosed) anemia; delaying revascularization to allow fast-track anemia diagnosis is usually feasible and justified in non-ST-elevation ACS. Besides identification and treatment of the underlying causes of anemia, the only readily available means to reverse anemia is red blood cell transfusion. The adequate transfusion threshold is still being debated, although solid evidence suggests reserving red blood cell transfusions for patients with Hb level <8 g/dL and considering it in selected cases with Hb levels of between 8 and 10 g/dL. No evidence supports the use of iron supplements and erythropoiesis-stimulating agents in the setting of ACS
Faraday rotation, stochastic magnetic fields and CMB maps
The high- and low-frequency descriptions of the pre-decoupling plasma are
deduced from the Vlasov-Landau treatment generalized to curved space-times and
in the presence of the relativistic fluctuations of the geometry. It is
demonstrated that the interplay between one-fluid and two-fluid treatments is
mandatory for a complete and reliable calculation of the polarization
observables. The Einstein-Boltzmann hierarchy is generalized to handle the
dispersive propagation of the electromagnetic disturbances in the
pre-decoupling plasma. Given the improved physical and numerical framework, the
polarization observables are computed within the magnetized CDM
paradigm (mCDM). In particular, the Faraday-induced B-mode is
consistently estimated by taking into account the effects of the magnetic
fields on the initial conditions of the Boltzmann hierarchy, on the dynamical
equations and on the dispersion relations. The complete calculations of the
angular power spectra constitutes the first step for the derivation of
magnetized maps of the CMB temperature and polarization which are here obtained
for the first time and within the minimal mCDM model. The obtained
results set the ground for direct experimental scrutiny of large-scale
magnetism via the low and high frequency instruments of the Planck explorer
satellite.Comment: 53 pages, 15 included figure
Fermion scattering off electroweak phase transition kink walls with hypermagnetic fields
We study the scattering of fermions off a finite width kink wall during the
electroweak phase transition in the presence of a background hypermagnetic
field. We derive and solve the Dirac equation for such fermions and compute the
reflection and transmission coefficients for the case when the fermions move
from the symmetric to the broken symmetry phase. We show that the chiral nature
of the fermion coupling with the background field in the symmetric phase
generates an axial asymmetry in the scattering processes. We discuss possible
implications of such axial charge segregation for baryon number generation.Comment: 9 pages, 3 Postscript figures, uses RevTeX4. Expanded discussion,
published versio
Dynamics of the Energy Transfer Process in Eu(III) Complexes Containing Polydentate Ligands Based on Pyridine, Quinoline, and Isoquinoline as Chromophoric Antennae
In this work, we investigated from a theoretical point of view the dynamics of the energy transfer process from the ligand to Eu(III) ion for 12 isomeric species originating from six different complexes differing by nature of the ligand and the total charge. The cationic complexes present the general formula [Eu(L)(H2O)2]+ (where L = bpcd2- = N,N'-bis(2-pyridylmethyl)-trans-1,2-diaminocyclohexane N,N'-diacetate; bQcd2- = N,N'-bis(2-quinolinmethyl)-trans-1,2-diaminocyclohexane N,N'-diacetate; and bisoQcd2- = N,N'-bis(2-isoquinolinmethyl)-trans-1,2-diaminocyclohexane N,N'-diacetate), while the neutral complexes present the Eu(L)(H2O)2 formula (where L = PyC3A3- = N-picolyl-N,N',N'-trans-1,2-cyclohexylenediaminetriacetate; QC3A3- = N-quinolyl-N,N',N'-trans-1,2-cyclohexylenediaminetriacetate; and isoQC3A3- = N-isoquinolyl-N,N',N'-trans-1,2-cyclohexylenediaminetriacetate). Time-dependent density functional theory (TD-DFT) calculations provided the energy of the ligand excited donor states, distances between donor and acceptor orbitals involved in the energy transfer mechanism (RL), spin-orbit coupling matrix elements, and excited-state reorganization energies. The intramolecular energy transfer (IET) rates for both singlet-triplet intersystem crossing and ligand-to-metal (and vice versa) involving a multitude of ligand and Eu(III) levels and the theoretical overall quantum yields (ϕovl) were calculated (the latter for the first time without the introduction of experimental parameters). This was achieved using a blend of DFT, Judd-Ofelt theory, IET theory, and rate equation modeling. Thanks to this study, for each isomeric species, the most efficient IET process feeding the Eu(III) excited state, its related physical mechanism (exchange interaction), and the reasons for a better or worse overall energy transfer efficiency (ηsens) in the different complexes were determined. The spectroscopically measured ϕovl values are in good agreement with the ones obtained theoretically in this work
Cross-sectional survey of users of internet depression communities
Background: Internet-based depression communities provide a forum for individuals to
communicate and share information and ideas. There has been little research into the health status
and other characteristics of users of these communities.
Methods: Online cross-sectional survey of Internet depression communities to identify depressive
morbidity among users of Internet depression communities in six European countries; to
investigate whether users were in contact with health services and receiving treatment; and to
identify user perceived effects of the communities.
Results: Major depression was highly prevalent among respondents (varying by country from 40%
to 64%). Forty-nine percent of users meeting criteria for major depression were not receiving
treatment, and 35% had no consultation with health services in the previous year. Thirty-six
percent of repeat community users who had consulted a health professional in the previous year
felt that the Internet community had been an important factor in deciding to seek professional help.
Conclusions: There are high levels of untreated and undiagnosed depression in users of Internet
depression communities. This group represents a target for intervention. Internet communities can
provide information and support for stigmatizing conditions that inhibit more traditional modes of
information seeking
Functional analysis of novel KCNQ2 and KCNQ3 gene variants found in a large pedigree with benign familial neonatal convulsions (BFNC)
Benign familial neonatal convulsion (BFNC) is a rare autosomal dominant disorder caused by mutations in KCNQ2 and KCNQ3, two genes encoding for potassium channel subunits. A large family with nine members affected by BFNC is described in the present study. All affected members of this family carry a novel deletion/insertion mutation in the KCNQ2 gene (c.761_770del10insA), which determines a premature truncation of the protein. In addition, in the family of the proposita's father, a novel sequence variant (c.2687A>G) in KCNQ3 leading to the p.N821S amino acid change was detected. When heterologously expressed in Chinese hamster ovary cells, KCNQ2 subunits carrying the mutation failed to form functional potassium channels in homomeric configuration and did not affect channels formed by KCNQ2 and/or KCNQ3 subunits. On the other hand, homomeric and heteromeric potassium channels formed by KCNQ3 subunits carrying the p.N821S variant were indistinguishable from those formed by wild-type KCNQ3 subunits. Finally, the current density of the cells mimicking the double heterozygotic condition for both KCNQ2 and KCNQ3 alleles of the proband was decreased by approximately 25% when compared to cells expressing only wild-type alleles. Collectively, these results suggest that, in the family investigated, the KCNQ2 mutation is responsible for the BFNC phenotype, possibly because of haplo-insufficiency, whereas the KCNQ3 variant is functionally silent, a result compatible with its lack of segregation with the BFNC phenotyp
Measurements of ZnWO anisotropic response to nuclear recoils for the ADAMO project
Anisotropic scintillators can offer a unique possibility to exploit the
so-called directionality approach in order to investigate the presence of those
Dark Matter (DM) candidates inducing nuclear recoils. In fact, their use can
overcome the difficulty of detecting extremely short nuclear recoil traces. In
this paper we present recent measurements performed on the anisotropic response
of a ZnWO crystal scintillator to nuclear recoils, in the framework of the
ADAMO project. The anisotropic features of the ZnWO crystal scintillators
were initially measured with particles; those results have been also
confirmed by the additional measurements presented here. The experimental
nuclear recoil data were obtained by using a neutron generator at ENEA-CASACCIA
and neutron detectors to tag the scattered neutrons; in particular, the
quenching factor values for nuclear recoils along different crystallographic
axes have been determined for three different neutron scattering angles (i.e.
nuclear recoils energies). From these measurements, the anisotropy of the light
response for nuclear recoils in the ZnWO crystal scintillator has been
determined at 5.4 standard deviations.Comment: 22 pages; 12 figures. In press on Eur. Phys. J.
Developments and improvements of radiopure ZnWO anisotropic scintillators
The ZnWO is an anisotropic crystal scintillator; for its peculiar
characteristics, it is a very promising detector to exploit the so-called
directionality approach in the investigation of those Dark Matter (DM)
candidates inducing nuclear recoils. Recently, in the framework of the ADAMO
project, an R\&D to develop high quality and ultra-radiopure ZnWO crystal
scintillators has been carried out. In the present paper the measurements to
study the anisotropic response of a ZnWO to particles and to
nuclear recoils induced by neutron scattering are reported. Monochromatic
neutrons have been produced by a neutron generator at ENEA-CASACCIA. The
quenching factor values for nuclear recoils along different crystallographic
axes have been determined for three different nuclear recoils energies. These
results open the possibility to realize a pioneer experiment to investigate the
above mentioned DM candidates by means of the directionality.Comment: Proceedings of the IPRD 2019 Conference, 10 pages, 7 figures,
accepted for publication in JINS
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