2,381 research outputs found
A Practical and Efficient Synthesis of Uniform Conjugated Rod‐Like Oligomers
Herein, a more practical and efficient synthesis protocol for the preparation of uniform rod-like oligo(1,4-phenylene ethynylene)s (OPE)s is presented. Applying an iterative reaction cycle consisting of a decarboxylative coupling reaction and a saponification of an alkynyl carboxylic ester, a uniform pentamer is obtained in ten steps with 14% overall yield. The copper-free conditions prevent homocoupling until the trimer stage, resulting in a significantly easier work-up of the products. Homocoupling is observed from the tetramer stage on, but a simple variation of the work-up procedure also yields the uniform tetramer and pentamer. A thorough comparison with the commonly used and described Sonogashira approach reveals that with the new presented strategy, OPEs can be built in similar overall yield, but easier purification and in a quarter of the time. All oligomers are fully characterized by proton and carbon nuclear magnetic resonance spectroscopy (NMR), mass spectrometry (MS), size-exclusion chromatography (SEC), and infrared spectroscopy (IR)
Magnetization transport and quantized spin conductance
We analyze transport of magnetization in insulating systems described by a
spin Hamiltonian. The magnetization current through a quasi one-dimensional
magnetic wire of finite length suspended between two bulk magnets is determined
by the spin conductance which remains finite in the ballistic limit due to
contact resistance. For ferromagnetic systems, magnetization transport can be
viewed as transmission of magnons and the spin conductance depends on the
temperature T. For antiferromagnetic isotropic spin-1/2 chains, the spin
conductance is quantized in units of order at T=0.
Magnetization currents produce an electric field and hence can be measured
directly. For magnetization transport in electric fields phenomena analogous to
the Hall effect emerge.Comment: 4 pages, 3 figures, minor change
Dispensed drugs during pregnancy in outpatient care between 2015 and 2021 in Switzerland: a retrospective analysis of Swiss healthcare claims data.
AIM OF THE STUDY
We aimed to evaluate the utilisation of all prescribed drugs during pregnancy dispensed in outpatient care in Switzerland between 2015 and 2021.
METHODS
We conducted a descriptive study using the Swiss Helsana claims database (2015-2021). We established a cohort of pregnancies by identifying deliveries and estimating the date of the last menstrual period. We analysed the drug burden during a 270-day pre-pregnancy period, during pregnancy (overall and by trimester), and during a 270-day postpartum period. Subsequently, we quantified 1) the median number of drug dispensations (total vs. unique drug claims); and 2) the prevalence of exposure to at least one dispensed drug and the number of dispensed drugs (0, 1, 2, 3, 4, and ≥5); and 3) the 15 most frequently dispensed drugs were identified during each period, overall and stratified by maternal age.
RESULTS
Among 34,584 pregnant women (5.6% of all successful pregnancies in Switzerland), 87.5% claimed at least one drug (not including vitamins, supplements, and vaccines), and 33.3% claimed at least five drugs during pregnancy. During trimester 1 alone, 8.2% of women claimed at least five distinct drugs. The proportion of women who claimed prescribed drugs was lower pre-pregnancy (69.1%) and similar postpartum (85.6%) when compared to during pregnancy (87.5%). The most frequently claimed drugs during pregnancy were meaningfully different during pregnancy than before and after.
CONCLUSIONS
This study suggests that 8 of 10 women in Switzerland are exposed to prescribed drugs during pregnancy. Most drugs dispensed during pregnancy are comparatively well investigated and are considered safe. However, the high drug burden in this vulnerable patient population underlines the importance of evidence on the benefit-risk profile of individual drugs taken during pregnancy
Leggett Modes Accompanying Crystallographic Phase Transitions
Higgs and Goldstone modes, well known in high-energy physics, have been realized in a number of condensed matter physics contexts, including superconductivity and magnetism. The Goldstone-Higgs concept is also applicable to and gives rise to new insight on structural phase transitions. Here, we show that the Leggett mode, a collective mode observed in multiband superconductors, also has an analog in crystallographic phase transitions. Such structural Leggett modes can occur in the phase channel as in the original work of Leggett [Prog. Theor. Phys. 36, 901 (1966)PTPKAV0033-068X10.1143/PTP.36.901]. That is, they are antiphase Goldstone modes (antiphasons). In addition, a new collective mode can also occur in the amplitude channel, an out-of phase (antiphase) Higgs mode, that should be observable in multiband superconductors as well. We illustrate the existence and properties of these structural Leggett modes using the example of the pyrochlore relaxor ferroelectric Cd2Nb2O7
Ovarian activity in Fleckvieh, Brown Swiss and two strains of Holstein-Friesian cows in pasture-based, seasonal calving dairy systems
The objectives of the study were to compare the ovarian activity of Holstein-Friesian (CH HF), Fleckvieh (CH FV) and Brown Swiss (CH BS) dairy cows of Swiss origin with that of Holstein-Friesian (NZ HF) dairy cows of New Zealand origin, the latter being used as a reference for reproductive performance in pasture-based seasonal calving systems. Fifty, second-lactation NZ HF cows were each paired with a second-lactation Swiss cow (17, 15 and 18 CH HF, CH FV and CH BS respectively) in 13 pasture-based, seasonal-calving commercial dairy farms in Switzerland. Ovarian activity was monitored by progesterone profiling from calving to first breeding service. CH BS cows produced less energy-corrected milk (mean 22·8 kg/d) than the other breeds (26·0-26·5 kg/d) during the first 100 d of lactation. CH HF cows had the lowest body condition score (BCS) at calving and the greatest BCS loss from calving to 30 d post partum. Commencement of luteal activity (CLA) was later for NZ HF than for CH FV (51·5 v. 29·2 d; P <0·01), with CH HF and CH BS intermediate (43 d). On average, NZ HF and CH HF cows had one oestrous cycle before the onset of the seasonal breeding period; this was less (P<0·01) than either CH FV (1·7) or CH BS (1·6). There was a low prevalence of luteal persistency (3%) among the studied cows. First and second oestrous cycle inter-ovulatory intervals did not differ between breeds (20·5-22·6 d). The luteal phase length of CH BS during the second cycle was shorter (10·6 d) than that of the other breeds (13·8-16·0 d), but the inter-luteal interval was longer (9·8 d v. 7·0-8·0 d). The results suggest that the Swiss breeds investigated have a shorter interval from calving to CLA than NZ HF cow
Imaging Carbon Monoxide Emission in the Starburst Galaxy NGC 6000
We present measurements of carbon monoxide emission in the central region of
the nearby starburst NGC 6000 taken with the Submillimeter Array. The J=2-1
transition of 12CO, 13CO, and C18O were imaged at a resolution of ~3''x2''
(450x300 pc). We accurately determine the dynamical center of NGC 6000 at
R.A(J2000.0)=15h49m49.5s and dec(J2000.0)=-29d23'13'' which agrees with the
peak of molecular emission position. The observed CO dynamics could be
explained in the context of the presence of a bar potential affecting the
molecular material, likely responsible for the strong nuclear concentration
where more than 85% of the gas is located. We detect a kinematically detached
component of dense molecular gas at relatively high velocity which might be
fueling the star formation. A total nuclear dynamical mass of 7x10^9 Msun is
derived and a total mass of gas of 4.6x10^8 Msun, yielding a Mgas/Mdyn~6%,
similar to other previously studied barred galaxies with central starbursts. We
determined the mass of molecular gas with the optically thin isotopologue C18O
and we estimate a CO-to-H2 conversion factor X(CO)=0.4x10^20 cm-2/(K km s-1) in
agreement with that determined in other starburst galaxies.Comment: 31 pages, 7 figures. Accepted for publication in Astronomical
Journal
Reduced functional measure of cardiovascular reserve predicts admission to critical care unit following kidney transplantation
Background: There is currently no effective preoperative assessment for patients undergoing kidney transplantation that is
able to identify those at high perioperative risk requiring admission to critical care unit (CCU). We sought to determine if
functional measures of cardiovascular reserve, in particular the anaerobic threshold (VO2AT) could identify these patients.
Methods: Adult patients were assessed within 4 weeks prior to kidney transplantation in a University hospital with a 37-bed
CCU, between April 2010 and June 2012. Cardiopulmonary exercise testing (CPET), echocardiography and arterial
applanation tonometry were performed.
Results: There were 70 participants (age 41.7614.5 years, 60% male, 91.4% living donor kidney recipients, 23.4% were
desensitized). 14 patients (20%) required escalation of care from the ward to CCU following transplantation. Reduced
anaerobic threshold (VO2AT) was the most significant predictor, independently (OR = 0.43; 95% CI 0.27–0.68; p,0.001) and
in the multivariate logistic regression analysis (adjusted OR = 0.26; 95% CI 0.12–0.59; p = 0.001). The area under the receiveroperating-
characteristic curve was 0.93, based on a risk prediction model that incorporated VO2AT, body mass index and
desensitization status. Neither echocardiographic nor measures of aortic compliance were significantly associated with CCU
admission.
Conclusions: To our knowledge, this is the first prospective observational study to demonstrate the usefulness of CPET as a
preoperative risk stratification tool for patients undergoing kidney transplantation. The study suggests that VO2AT has the
potential to predict perioperative morbidity in kidney transplant recipients
Quantum computing with antiferromagnetic spin clusters
We show that a wide range of spin clusters with antiferromagnetic
intracluster exchange interaction allows one to define a qubit. For these spin
cluster qubits, initialization, quantum gate operation, and readout are
possible using the same techniques as for single spins. Quantum gate operation
for the spin cluster qubit does not require control over the intracluster
exchange interaction. Electric and magnetic fields necessary to effect quantum
gates need only be controlled on the length scale of the spin cluster rather
than the scale for a single spin. Here, we calculate the energy gap separating
the logical qubit states from the next excited state and the matrix elements
which determine quantum gate operation times. We discuss spin cluster qubits
formed by one- and two-dimensional arrays of s=1/2 spins as well as clusters
formed by spins s>1/2. We illustrate the advantages of spin cluster qubits for
various suggested implementations of spin qubits and analyze the scaling of
decoherence time with spin cluster size.Comment: 15 pages, 7 figures; minor change
Bone health in patients with inflammatory bowel disease.
Patients with inflammatory bowel disease (IBD) are prone to reduced bone mineral density and elevated overall fracture risk. Osteopenia affects up to 40% of patients with IBD (high regional variability). Besides disease activity, IBD specialists must consider possible side effects of medication and the presence of associated diseases and extraintestinal manifestations. Osteopenia and osteoporosis remain frequent problems in patients with IBD and are often underestimated because of widely differing screening and treatment practices. Malnutrition, chronic intestinal inflammation and corticosteroid intake are the major pathophysiological factors contributing to osteoporosis. Patients with IBD are screened for osteoporosis using dual-energy X-ray absorptiometry (DXA), which is recommended for all patients with a prolonged disease course of more than three months, with repeated corticosteroid administration, aged >40 years with a high FRAX risk score or aged <40 years with multiple risk factors. From a therapeutic perspective, besides good disease control, vitamin D supplementation and glucocorticoid sparing, several specific osteological options are available: bisphosphonates, receptor activator of nuclear factor kappa-B ligand (RANKL) inhibitors (denosumab), parathyroid hormone (PTH) analogues and selective estrogen receptor modulators. This review provides an overview of the pathophysiology, diagnosis, prevention and treatment of IBD-associated bone loss
- …