5,298 research outputs found
Estimation of the hydraulic parameters of unsaturated samples by electrical resistivity tomography
In situ and laboratory experiments have shown that electrical resistivity tomography (ERT) is an effective tool to image transient phenomena in soils. However, its application in quantifying soil hydraulic parameters has been limited. In this study, experiments of water inflow in unsaturated soil samples were conducted in an oedometer equipped to perform three-dimensional electrical measurements. Reconstructions of the electrical conductivity at different times confirmed the usefulness of ERT for monitoring the evolution of water content. The tomographic reconstructions were subsequently used in conjunction with a finite-element simulation to infer the water retention curve and the unsaturated hydraulic conductivity. The parameters estimated with ERT agree satisfactorily with those determined using established techniques, hence the proposed approach shows good potential for relatively fast characterisations. Similar experiments could be carried out on site to study the hydraulic behaviour of the entire soil deposi
Well-Tempered Metadynamics Simulations Predict the Structural and Dynamic Properties of a Chiral 24-Atom Macrocycle in Solution
Inspired by therapeutic potential, the molecular engineering of macrocycles is garnering increased interest. Exercising control with design, however, is challenging due to the dynamic behavior that these molecules must demonstrate in order to be bioactive. Herein, the value of metadynamics simulations is demonstrated: the free-energy surfaces calculated reveal folded and flattened accessible conformations of a 24-atom macrocycle separated by barriers of c.a. 6 kT under experimentally relevant conditions. Simulations reveal that the dominant conformer is folded-an observation consistent with a solid-state structure determined by X-ray crystallography and a network of rOes established by 1H NMR. Simulations suggest that the macrocycle exists as a rapidly interconverting pair of enantiomeric, folded structures. Experimentally, 1H NMR shows a single species at room temperature. However, at lower temperature, the interconversion rate between these enantiomers becomes markedly slower, resulting in the decoalescence of enantiotopic methylene protons into diastereotopic, distinguishable resonances due to the persistence of conformational chirality. The emergence of conformational chirality provides critical experimental support for the simulations, revealing the dynamic nature of the scaffold-a trait deemed critical for oral bioactivity
Mass-luminosity relation for FGK main sequence stars: metallicity and age contributions
The stellar mass-luminosity relation (MLR) is one of the most famous
empirical "laws", discovered in the beginning of the 20th century. MLR is still
used to estimate stellar masses for nearby stars, particularly for those that
are not binary systems, hence the mass cannot be derived directly from the
observations. It's well known that the MLR has a statistical dispersion which
cannot be explained exclusively due to the observational errors in luminosity
(or mass). It is an intrinsic dispersion caused by the differences in age and
chemical composition from star to star. In this work we discuss the impact of
age and metallicity on the MLR. Using the recent data on mass, luminosity,
metallicity, and age for 26 FGK stars (all members of binary systems, with
observational mass-errors <= 3%), including the Sun, we derive the MLR taking
into account, separately, mass-luminosity, mass-luminosity-metallicity, and
mass-luminosity-metallicity-age. Our results show that the inclusion of age and
metallicity in the MLR, for FGK stars, improves the individual mass estimation
by 5% to 15%.Comment: 7 pages, 4 figures, 1 table, accepted in Astrophysics and Space
Scienc
On the Behavior of the Effective QCD Coupling alpha_tau(s) at Low Scales
The hadronic decays of the tau lepton can be used to determine the effective
charge alpha_tau(m^2_tau') for a hypothetical tau-lepton with mass in the range
0 < m_tau' < m_tau. This definition provides a fundamental definition of the
QCD coupling at low mass scales. We study the behavior of alpha_tau at low mass
scales directly from first principles and without any renormalization-scheme
dependence by looking at the experimental data from the OPAL Collaboration. The
results are consistent with the freezing of the physical coupling at mass
scales s = m^2_tau' of order 1 GeV^2 with a magnitude alpha_tau ~ 0.9 +/- 0.1.Comment: 15 pages, 4 figures, submitted to Physical Review D, added
references, some text added, no results nor figures change
Discovery of the 2010 Eruption and the Pre-Eruption Light Curve for Recurrent Nova U Scorpii
We report the discovery by B. G. Harris and S. Dvorak on JD 2455224.9385
(2010 Jan 28.4385 UT) of the predicted eruption of the recurrent nova U Scorpii
(U Sco). We also report on 815 magnitudes (and 16 useful limits) on the
pre-eruption light curve in the UBVRI and Sloan r' and i' bands from 2000.4 up
to 9 hours before the peak of the January 2010 eruption. We found no
significant long-term variations, though we did find frequent fast variations
(flickering) with amplitudes up to 0.4 mag. We show that U Sco did not have any
rises or dips with amplitude greater than 0.2 mag on timescales from one day to
one year before the eruption. We find that the peak of this eruption occurred
at JD 2455224.69+-0.07 and the start of the rise was at JD 2455224.32+-0.12.
From our analysis of the average B-band flux between eruptions, we find that
the total mass accreted between eruptions is consistent with being a constant,
in agreement with a strong prediction of nova trigger theory. The date of the
next eruption can be anticipated with an accuracy of +-5 months by following
the average B-band magnitudes for the next ~10 years, although at this time we
can only predict that the next eruption will be in the year 2020+-2.Comment: Astronomical Journal submitted, 36 pages, 3 figures, full table
Trends in incidence, treatment, survival and subsequent breast cancer in lobular carcinoma in situ in the Netherlands:A population-based analysis
Purpose: We analysed incidence, treatment, survival, occurrence of ductal carcinoma in situ (DCIS) and invasive breast cancer (IBC) after lobular carcinoma in situ (LCIS) in the Netherlands. Methods: All women diagnosed with classic LCIS between 1989 and 2017 were identified from the Netherlands Cancer Registry. We calculated overall (OS), relative survival (RS) and cumulative incidence functions (CIF, accounting for competing risks) of mortality, DCIS and IBC. For IBC, standardised incidence ratios (SIR) of IBC were calculated. Analyses were stratified for surgical treatment. Results: We included 1890 patients. Median age was 51 years. Median follow-up was 8.5 years. In 1989–2017, LCIS incidence increased from 41 to 124, surgical treatment decreased from 100% to 41.1 % – mostly BCS. 10-year OS and 20-year RS exceeded 90 % in all subgroups. Overall, 48 (2.5 %) and 270 (14.3 %) patients were diagnosed with DCIS and IBC. IBCs were mostly early-stage. After mastectomy, 13 of 14 IBCs presented contralaterally. In the other groups, 64.8–70.9 % of IBCs presented ipsilaterally, 34.5–53.9 % of these were lobular. The SIR of ipsilateral IBC was highest after no surgery (6.9, 95%CI:4.9–9.4), lowest after mastectomy (0.2, 95%CI:0.4–0.8). Conclusion: LCIS incidence increased, surgical treatment decreased. The low mortality risks support consideration of active surveillance. However, the increased IBC incidence suggests careful monitoring
A phase 1b study evaluating the effect of elacestrant treatment on estrogen receptor availability and estradiol binding to the estrogen receptor in metastatic breast cancer lesions using 18F-FES PET/CT imaging
Background: Elacestrant is an oral selective estrogen receptor (ER) degrader. This phase 1b open-label, non-randomized study (RAD1901-106) was initiated to determine the effect of elacestrant on the availability of ER in lesions from postmenopausal women with ER+ advanced breast cancer (ABC) using 16α-18F-fluoro-17β-estradiol positron emission tomography with low-dose computed tomography (FES-PET/CT). Methods: Eligible patients were postmenopausal women with ER+, HER2- ABC; tumor progression after ≥ 6 months of 1-3 lines of endocrine treatment for ABC; and measurable or evaluable disease. Two 8-patient cohorts were enrolled: one treated with 400 mg elacestrant once daily (QD) and one treated with 200 mg elacestrant QD with dose escalation to 400 mg QD after 14 days. Elacestrant was dosed continuously until progressive disease, toxicity, or withdrawal. FES-PET/CT was performed pre-dose at baseline and 4 h post-dose on day 14. The primary endpoint was the percentage difference in FES uptake in tumor lesions (maximum 20) after 14 days of treatment compared to baseline. Overall response was investigator-assessed by Response Evaluation Criteria in Solid Tumors [RECIST] version 1.1. Results: Patients (n = 16; median age, 53.5 years) had ABC with a median 2.5 prior lines of endocrine therapy. Median reduction in tumor FES uptake from baseline to day 14 was 89.1% (Q1, Q3: 75.1%, 94.1%) and was similar in both cohorts (89.1% [Q1, Q3: 67.4%, 94.2%], 200/400 mg and 88.7% [Q1, Q3: 79.5%, 94.1%], 400 mg). Residual ER availability (> 25% persistence in FES uptake) on day 14 was observed in 3 patients receiving 200/400 mg (3/78, 37.5%) and 1 patient receiving 400 mg (1/8, 12.5%). The overall response rate (ORR) was 11.1% (1 partial response), and clinical benefit rate (CBR) was 30.8%. Median percentage change in FES uptake did not correlate with ORR or CBR. Adverse events occurring in > 20% of the patients were nausea (68.8%), fatigue (50.0%), dyspepsia (43.8%), vomiting (37.5%), and decreased appetite, dysphagia, and hot flush (31.3% each). Most events were grade 2 in severity. Conclusion: Elacestrant 200 mg and 400 mg QD greatly reduced ER availability measured by FES-PET/CT. In a heavily pretreated population, elacestrant was associated with antitumor activity. Trial registration: ClinicalTrials.gov, NCT02650817. Registered on 08 January 201
Design and Process Development for Smart Phone Medication Dosing Support System and Educational Platform in HIV/Aids-TB Programs in Zambia
The widespread adoption of cell phones and other mobile platforms represents an opportunity to extend the benefits of personalized, point-of-care, healthcare applications to providers and patients in the developing world. However, the challenges facing the effective deployment of mobile health care applications are complex, and thus require a scalable, flexible, and configurable approach. A service-oriented-architecture-based conceptual framework is proposed to address the challenges of developing and deploying mobile health care applications. A particular emphasis of the framework is a service-agent-modeling-based composite process-personalization support that is needed to support the diverse and adaptable needs of the users
Bose-Einstein Correlations in e+e- to W+W- at 172 and 183 GeV
Bose-Einstein correlations between like-charge pions are studied in hadronic
final states produced by e+e- annihilations at center-of-mass energies of 172
and 183 GeV. Three event samples are studied, each dominated by one of the
processes W+W- to qqlnu, W+W- to qqqq, or (Z/g)* to qq. After demonstrating the
existence of Bose-Einstein correlations in W decays, an attempt is made to
determine Bose-Einstein correlations for pions originating from the same W
boson and from different W bosons, as well as for pions from (Z/g)* to qq
events. The following results are obtained for the individual chaoticity
parameters lambda assuming a common source radius R: lambda_same = 0.63 +- 0.19
+- 0.14, lambda_diff = 0.22 +- 0.53 +- 0.14, lambda_Z = 0.47 +- 0.11 +- 0.08, R
= 0.92 +- 0.09 +- 0.09. In each case, the first error is statistical and the
second is systematic. At the current level of statistical precision it is not
established whether Bose-Einstein correlations, between pions from different W
bosons exist or not.Comment: 24 pages, LaTeX, including 6 eps figures, submitted to European
Physical Journal
- …