1,348 research outputs found
Advances and visions in large-scale hydrological modelling: findings from the 11th Workshop on Large-Scale Hydrological Modelling
Large-scale hydrological modelling has become increasingly wide-spread during the last decade. An annual workshop series on large-scale hydrological modelling has provided, since 1997, a forum to the German-speaking community for discussing recent developments and achievements in this research area. In this paper we present the findings from the 2007 workshop which focused on advances and visions in large-scale hydrological modelling. We identify the state of the art, difficulties and research perspectives with respect to the themes "sensitivity of model results", "integrated modelling" and "coupling of processes in hydrosphere, atmosphere and biosphere". Some achievements in large-scale hydrological modelling during the last ten years are presented together with a selection of remaining challenges for the future
Frustration driven lattice distortion; an NMR investigation of Y2Mo2O7
We have investigated the 89Y NMR spectrum and spin lattice relaxation, T1, in
the magnetically frustrated pyrochlore Y2Mo2O7. We find that upon cooling the
spectrum shifts, and broadens asymmetrically. A detailed examination of the low
T spectrum reveals that it is constructed from multiple peaks, each shifted by
a different amount. We argue that this spectrum is due to discrete lattice
distortions, and speculate that these distortions relieve the frustration and
reduce the system's energy.Comment: To be published in Phys. Rev. Let
Solutions to Maxwell's Equations using Spheroidal Coordinates
Analytical solutions to the wave equation in spheroidal coordinates in the
short wavelength limit are considered. The asymptotic solutions for the radial
function are significantly simplified, allowing scalar spheroidal wave
functions to be defined in a form which is directly reminiscent of the
Laguerre-Gaussian solutions to the paraxial wave equation in optics.
Expressions for the Cartesian derivatives of the scalar spheroidal wave
functions are derived, leading to a new set of vector solutions to Maxwell's
equations. The results are an ideal starting point for calculations of
corrections to the paraxial approximation
Radiation therapy for vaginal and perirectal lesions in recurrent ovarian cancer
The role for localized radiation to treat ovarian cancer (OC) patients with locally recurrent vaginal/perirectal lesions remains unclear, though we hypothesize these patients may be salvaged locally and gain long-term survival benefit. We describe our institutional outcomes using intensity modulated radiation therapy (IMRT) +/- high-dose rate (HDR) brachytherapy to treat this population. Our primary objectives were to evaluate complete response rates of targeted lesions after radiation and calculate our 5-year in-field control (IFC) rate. Secondary objectives were to assess radiation-related toxicities, chemotherapy free-interval (CFI), as well as post-radiation progression-free (PFS) and overall survival (OS). PFS and OS were defined from radiation start to either progression or death/last follow-up, respectively. This was a heavily pre-treated cohort of 17 recurrent OC patients with a median follow-up of 28.4 months (range 4.5-166.4) after radiation completion. 52.9% had high-grade serous histology and 4 (23.5%) had isolated vaginal/perirectal disease. Four (23.5%) patients had in-field failures at 3.7, 11.2, 24.5, and 27.5 months after start of radiation, all treated with definitive dosing of radiation therapy. Patients who were platinum-sensitive prior to radiation had similar median PFS (6.5 vs. 13.4 months, log-rank p = 0.75), but longer OS (71.1 vs 18.8 months, log-rank p = 0.05) than their platinum-resistant counterparts. Excluding patients with low-grade histology or who were treated with palliative radiation, median CFI was 14.2 months (range 4.7 - 33.0). Radiation was well tolerated with 2 (12.0%) experiencing grade 3/4 gastrointestinal/genitourinary toxicities. In conclusion, radiation to treat locally recurrent vaginal/perirectal lesions in heavily pre-treated OC patients is safe and may effectively provide IFC
The Effect of Water on the 2-Propanol Oxidation Activity of Co-Substituted LaFe<sub>1â</sub>Co<sub>x</sub>O<sub>3</sub> Perovskites
Perovskites are interesting oxidation catalysts due to their chemical flexibility enabling the tuning of several properties. In this work, we synthesized LaFe1âxCoxO3 catalysts by co-precipitation and thermal decomposition, characterized them thoroughly and studied their 2-propanol oxidation activity under dry and wet conditions to bridge the knowledge gap between gas and liquid phase reactions. Transient tests showed a highly active, unstable low-temperature (LT) reaction channel in conversion profiles and a stable, less-active high-temperature (HT) channel. Cobalt incorporation had a positive effect on the activity. The effect of water was negative on the LT channel, whereas the HT channel activity was boosted for x > 0.15. The boost may originate from a slower deactivation rate of the Co3+ sites under wet conditions and a higher amount of hydroxide species on the surface comparing wet to dry feeds. Water addition resulted in a slower deactivation for Co-rich catalysts and higher activity in the HT channel state
Frustrated 3-Dimensional Quantum Spin Liquid in CuHpCl
Inelastic neutron scattering measurements are reported for the quantum
antiferromagnetic material Cu_2(C_5H_12N_2)_2Cl_4 (CuHpCl). The magnetic
excitation spectrum forms a band extending from 0.9 meV to 1.4 meV. The
spectrum contains two modes that disperse throughout the a-c plane of the
monoclinic unit cell with less dispersion along the unique b-axis. Simple
arguments based on the measured dispersion relations and the crystal structure
show that a spin ladder model is inappropriate for describing CuHpCl. Instead,
it is proposed that hydrogen bond mediated exchange interactions between the
bi-nuclear molecular units yield a three-dimensional interacting spin system
with a recurrent triangular motif similar to the Shastry-Sutherland Model
(SSM). Model independent analysis based on the first moment sum rule shows that
at least four distinct spin pairs are strongly correlated and that two of
these, including the dimer bond of the corresponding SSM, are magnetically
frustrated. These results show that CuHpCl should be classified as a
frustration induced three dimensional quantum spin liquid.Comment: 13 pages, 17 figures (Color) ReSubmitted to Phys. Rev. B 9/21/2001
resubmission has new content email comments to [email protected] or
[email protected]
Gynecologic oncology patient perspectives and knowledge on advance care planning: A quality improvement intervention
OBJECTIVES: Assess and improve advance care planning (ACP) awareness and uptake among gynecologic oncology patients.
METHODS: Using a quality improvement Plan-Do-Check-Act framework, we completed a single institution needs assessment and intervention. The needs assessment was a 26-question survey assessing baseline ACP knowledge and preferences of gynecologic oncology patients. We used this survey to implement an outpatient intervention in which patients were offered ACP resources (pamphlet, discussion with their gynecologic oncologist, and/or social work referral). We conducted a post-intervention survey among patients who had and had not received ACP resource(s) to assess whether our intervention increased ACP knowledge, discussions, or uptake.
RESULTS: Among 106 patients surveyed in the needs assessment, 33 % had ACP documents, 26 % had discussed ACP with a physician, and 82 % thought discussing ACP was important. The majority preferred these conversations in the outpatient setting (52 %) with their gynecologic oncologist (80 %) instead of nurses or trainees. In the intervention, 526 patients were offered ACP resources. Compared to women who did not receive resources (n = 324), patients who received ACP resource(s) (n = 202) were more likely to have ACP discussions with their gynecologic oncologist (38 % vs 68 %,
CONCLUSIONS: ACP uptake among gynecologic oncology patients is low, but ACP discussions with an oncologist during outpatient visits are important to patients and improve their knowledge regarding completing ACP documents
Fast Photon Detection for Particle Identification with COMPASS RICH-1
Particle identification at high rates is an important challenge for many
current and future high-energy physics experiments. The upgrade of the COMPASS
RICH-1 detector requires a new technique for Cherenkov photon detection at
count rates of several per channel in the central detector region, and a
read-out system allowing for trigger rates of up to 100 kHz. To cope with these
requirements, the photon detectors in the central region have been replaced
with the detection system described in this paper. In the peripheral regions,
the existing multi-wire proportional chambers with CsI photocathode are now
read out via a new system employing APV pre-amplifiers and flash ADC chips. The
new detection system consists of multi-anode photomultiplier tubes (MAPMT) and
fast read-out electronics based on the MAD4 discriminator and the F1-TDC chip.
The RICH-1 is in operation in its upgraded version for the 2006 CERN SPS run.
We present the photon detection design, constructive aspects and the first
Cherenkov light in the detector.Comment: Proceedings of the Imaging 2006 conference, Stockholm, Sweden, 27-30
June 2006, 5 pages, 6 figures, to appear in NIM A; corrected typo in caption
of Fig.
Fast photon detection for the COMPASS RICH detector
The COMPASS experiment at the SPS accelerator at CERN uses a large scale Ring
Imaging CHerenkov detector (RICH) to identify pions, kaons and protons in a
wide momentum range. For the data taking in 2006, the COMPASS RICH has been
upgraded in the central photon detection area (25% of the surface) with a new
technology to detect Cherenkov photons at very high count rates of several 10^6
per second and channel and a new dead-time free read-out system, which allows
trigger rates up to 100 kHz. The Cherenkov photons are detected by an array of
576 visible and ultra-violet sensitive multi-anode photomultipliers with 16
channels each. The upgraded detector showed an excellent performance during the
2006 data taking.Comment: Proceeding of the IPRD06 conference (Siena, Okt. 06
The Fast Read-out System for the MAPMTs of COMPASS RICH-1
A fast readout system for the upgrade of the COMPASS RICH detector has been
developed and successfully used for data taking in 2006 and 2007. The new
readout system for the multi-anode PMTs in the central part of the photon
detector of the RICH is based on the high-sensitivity MAD4
preamplifier-discriminator and the dead-time free F1-TDC chip characterized by
high-resolution. The readout electronics has been designed taking into account
the high photon flux in the central part of the detector and the requirement to
run at high trigger rates of up to 100 kHz with negligible dead-time. The
system is designed as a very compact setup and is mounted directly behind the
multi-anode photomultipliers. The data are digitized on the frontend boards and
transferred via optical links to the readout system. The read-out electronics
system is described in detail together with its measured performances.Comment: Proceeding of RICH2007 Conference, Trieste, Oct. 2007. v2: minor
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