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Synthesis and Study of Olefin Metathesis Catalysts Supported by Redox-Switchable Diaminocarbene 3 Ferrocenophanes
A redox-switchable ligand, N,N'-dimethyldiaminocarbene[3]ferrocenophane (5), was synthesized and incorporated into a series of Ir- and Ru-based complexes. Electrochemical and spectroscopic analyses of (5) Ir(CO)(2)Cl (15) revealed that 5 displayed a Tolman electronic parameter value of 2050 cm(-1) in the neutral state and 2061 cm(-1) upon oxidation. Moreover, inspection of X-ray crystallography data recorded for (5) Ir(cis,cis-1,5-cyclooctadiene)Cl (13) revealed that 5 was sterically less bulky (%V-Bur = 28.4) than other known diaminocarbene[3]ferrocenophanes, which facilitated the synthesis of (5)(PPh3)Cl2Ru-(3-phenylindenylid-1-ene) (18). Complex 18 exhibited quasi-reversible electrochemical processes at 0.79 and 0.98 V relative to SCE, which were assigned to the Fe and Ru centers in the complex, respectively, based on UV-vis and electron pair resonance spectroscopic measurements. Adding 2,3-dichloro-5,6-dicyanoquinone over the course of a ring-opening metathesis polymerization of cis, cis-1,5-cyclooctadiene catalyzed by 18 ([monomer](0)/[18](0) = 2500) reduced the corresponding rate constant of the reaction by over an order of magnitude (pre-oxidation: k(obs) = 0.045 s(-1); post-oxidation: k(obs) = 0.0012 s(-1)). Subsequent reduction of the oxidized species using decamethylferrocene restored catalytic activity (post-reduction: k(obs) = up to 0.016 s(-1), depending on when the reductant was added). The difference in the polymerization rates was attributed to the relative donating ability of the redox-active ligand (i.e., strongly donating 5 versus weakly donating 5(+)) which ultimately governed the activity displayed by the corresponding catalyst.U. S. Army Research Office W911NF-09-1-0446Chemistr
Uncertainty in multitask learning: joint representations for probabilistic MR-only radiotherapy planning
Multi-task neural network architectures provide a mechanism that jointly
integrates information from distinct sources. It is ideal in the context of
MR-only radiotherapy planning as it can jointly regress a synthetic CT (synCT)
scan and segment organs-at-risk (OAR) from MRI. We propose a probabilistic
multi-task network that estimates: 1) intrinsic uncertainty through a
heteroscedastic noise model for spatially-adaptive task loss weighting and 2)
parameter uncertainty through approximate Bayesian inference. This allows
sampling of multiple segmentations and synCTs that share their network
representation. We test our model on prostate cancer scans and show that it
produces more accurate and consistent synCTs with a better estimation in the
variance of the errors, state of the art results in OAR segmentation and a
methodology for quality assurance in radiotherapy treatment planning.Comment: Early-accept at MICCAI 2018, 8 pages, 4 figure
Double-Occupancy Errors, Adiabaticity, and Entanglement of Spin-Qubits in Quantum Dots
Quantum gates that temporarily increase singlet-triplet splitting in order to
swap electronic spins in coupled quantum dots, lead inevitably to a finite
double-occupancy probability for both dots. By solving the time-dependent
Schr\"odinger equation for a coupled dot model, we demonstrate that this does
not necessarily lead to quantum computation errors. Instead, the coupled dot
ground state evolves quasi-adiabatically for typical system parameters so that
the double-occupancy probability at the completion of swapping is negligibly
small. We introduce a measure of entanglement which explicitly takes into
account the possibilty of double occupancies and provides a necessary and
sufficient criterion for entangled states.Comment: 9 pages, 4 figures include
Simulating noise on a quantum processor: interactions between a qubit and resonant two-level system bath
Material defects fundamentally limit the coherence times of superconducting
qubits, and manufacturing completely defect-free devices is not yet possible.
Therefore, understanding the interactions between defects and a qubit in a real
quantum processor design is essential. We build a model that incorporates the
standard tunneling model, the electric field distributions in the qubit, and
open quantum system dynamics, and draws from the current understanding of
two-level system (TLS) theory. Specifically, we start with one million TLSs
distributed on the surface of a qubit and pick the 200 systems that are most
strongly coupled to the qubit. We then perform a full Lindbladian simulation
that explicitly includes the coherent coupling between the qubit and the TLS
bath to model the time dependent density matrix of resonant TLS defects and the
qubit. We find that the 200 most strongly coupled TLSs can accurately describe
the qubit energy relaxation time. This work confirms that resonant TLSs located
in areas where the electric field is strong can significantly affect the qubit
relaxation time, even if they are located far from the Josephson junction.
Similarly, a strongly-coupled resonant TLS located in the Josephson junction
does not guarantee a reduced qubit relaxation time if a more strongly coupled
TLS is far from the Josephson junction. In addition to the coupling strengths
between TLSs and the qubit, the model predicts that the geometry of the device
and the TLS relaxation time play a significant role in qubit dynamics. Our work
can provide guidance for future quantum processor designs with improved qubit
coherence times.Comment: 8 pages, 5 figure
Just-In-Time eTraining Applied To Emergency Medical Services
While the applications of just-in-time training are more and
more spread, the ubiquitous mobile technology has not found
practical uses of this training strategy. As an original example
of services for healthcare, we present in this work an
application of eTraining that makes use of mobile telephones
to transmit medical and on-site information content to
emergency medical personnel that attend and emergency. The
state-of-the-art in related technologies, overall architecture, and
functioning of JITTER (for Just-In-Time Training for
Emergency Responders) is described in this work.Universidad de Málaga. Campus de Excelencia Internacional AndalucĂa Tech. This work has been funded by the FIT-350100-2006-400
PROFIT project of the Spanish Ministerio de Industria,
Turismo y Comercio, American NSF grant DMI-0239180,
NIEHS (National Institute for Environmental Health
Sciences) grant 1R41ES014793-01, BanDeMar Networks,
Inc., the healthcare company iSOFT Sanidad, S.A., and the
CITIC Technology Centre
Significance of Travel to Rural Areas as a Risk Factor for Malarial Anemia in an Urban Setting
Disclaimer: This manuscript was published with the approval of the
Director of the Kenya Medical Research Institute. The findings and
conclusions in this report are those of the author(s) and do not necessarily
represent the views of the Centers for Disease Control and
Prevention.The epidemiology of malaria in urban environments is poorly characterized, yet increasingly problematic.
We conducted an unmatched case–control study of risk factors for malarial anemia with high parasitemia in urban
Kisumu, Kenya, from June 2002 through February 2003. Cases (n = 80) were hospital patients with a hemoglobin level
<= 8 g/dL and a Plasmodium parasite density ≥ 10,000/μL. Controls (n = 826) were healthy respondents to a concurrent
citywide knowledge, attitude, and practice survey. Children who reported spending at least one night per month in a rural
area were especially at risk (35% of cases; odds ratio = 9.3, 95% confidence interval [CI] = 4.4–19.7, P < 0.0001), and use
of mosquito coils, bed net ownership, and house construction were non-significant, potentially indicating that malaria
exposure during rural travel comprises an important element of risk. Control of severe malaria in an urban setting may be
complicated by Plasmodium infections acquired elsewhere. Epidemiologic studies of urban malaria in low transmission
settings should take travel history into account.This research was supported by CDC/KEMRI
and by the University of Michigan through the Rackham Graduate School, the Center for Research on Ethnicity, Culture and Health, and
the Global Health Program.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/91955/1/2010 AJTMH Significance of Travel to Rural Areas as a Risk Factor for Malarial Anemia in an Urban Setting.pd
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