Closed form solution for a double quantum well using Gr\"obner basis

Analytical expressions for spectrum, eigenfunctions and dipole matrix elements of a square double quantum well (DQW) are presented for a general case when the potential in different regions of the DQW has different heights and effective masses are different. This was achieved by Gr\"obner basis algorithm which allows to disentangle the resulting coupled polynomials without explicitly solving the transcendental eigenvalue equation.Comment: 4 figures, Mathematica full calculation noteboo

A new cosmological tracker solution for Quintessence

In this paper we propose a quintessence model with the potential $V(\Phi )=V_{o}[ \sinh {(\alpha \sqrt{\kappa_{o}}\Delta \Phi})] ^{\beta}$, which asymptotic behavior corresponds to an inverse power-law potential at early times and to an exponential one at late times. We demonstrate that this is a tracker solution and that it could have driven the Universe into its current inflationary stage. The exact solutions and the description for a complete evolution of the Universe are also given. We compare such model with the current cosmological observations.Comment: 13 pages REVTeX, 5 eps color figure

Galaxy And Mass Assembly (GAMA): testing galaxy formation models through the most massive galaxies in the Universe

We have analysed the growth of Brightest Group Galaxies and Brightest Cluster Galaxies (BGGs/BCGs) over the last 3 billion years using a large sample of 883 galaxies from the Galaxy And Mass Assembly survey. By comparing the stellar mass of BGGs and BCGs in groups and clusters of similar dynamical masses, we find no significant growth between redshift z = 0.27 and 0.09. We also examine the number of BGGs/BCGs that have line emission, finding that approximately 65 per cent of BGGs/BCGs show Hα in emission. From the galaxies where the necessary spectroscopic lines were accurately recovered (54 per cent of the sample), we find that half of this (i.e. 27 per cent of the sample) harbour ongoing star formation with rates up to 10 M⊙ yr−1, and the other half (i.e. 27 per cent of the sample) have an active nucleus (AGN) at the centre. BGGs are more likely to have ongoing star formation, while BCGs show a higher fraction of AGN activity. By examining the position of the BGGs/BCGs with respect to their host dark matter halo, we find that around 13 per cent of them do not lie at the centre of the dark matter halo. This could be an indicator of recent cluster–cluster mergers. We conclude that BGGs and BCGs acquired their stellar mass rapidly at higher redshifts as predicted by semi-analytic models, mildly slowing down at low redshifts

JWST/NIRCam Transmission Spectroscopy of the Nearby Sub-Earth GJ 341b

We present a JWST/NIRCam transmission spectrum from $3.9-5.0$ $\mu$m of the recently-validated sub-Earth GJ 341b ($\mathrm{R_P} = 0.92$ $\mathrm{R_{\oplus}}$, $\mathrm{T_{eq}} = 540$ K) orbiting a nearby bright M1 star ($\mathrm{d} = 10.4$ pc, $\mathrm{K_{mag}}=5.6$). We use three independent pipelines to reduce the data from the three JWST visits and perform several tests to check for the significance of an atmosphere. Overall, our analysis does not uncover evidence of an atmosphere. Our null hypothesis tests find that none of our pipelines' transmission spectra can rule out a flat line, although there is weak evidence for a Gaussian feature in two spectra from different pipelines (at 2.3 and $2.9\sigma$). However, the candidate features are seen at different wavelengths (4.3 $\mu$m vs 4.7 $\mu$m), and our retrieval analysis finds that different gas species can explain these features in the two reductions (CO$_2$ at $3.1\sigma$ compared to O$_3$ at $2.9\sigma$), suggesting that they are not real astrophysical signals. Our forward model analysis rules out a low mean molecular weight atmosphere ($< 350\times$ solar metallicity) to at least $3\sigma$, and disfavors CH$_4$-dominated atmospheres at $1-3\sigma$, depending on the reduction. Instead, the forward models find our transmission spectra are consistent with no atmosphere, a hazy atmosphere, or an atmosphere containing a species that does not have prominent molecular bands across the NIRCam/F444W bandpass, such as a water-dominated atmosphere. Our results demonstrate the unequivocal need for two or more transit observations analyzed with multiple reduction pipelines, alongside rigorous statistical tests, to determine the robustness of molecular detections for small exoplanet atmospheres.Comment: 25 pages, 18 figures, 6 tables. Accepted for publication in A

High tide or riptide on the cosmic shoreline? A water-rich atmosphere or stellar contamination for the warm super-Earth GJ 486b from JWST observations

Planets orbiting M-dwarf stars are prime targets in the search for rocky exoplanet atmospheres. The small size of M dwarfs renders their planets exceptional targets for transmission spectroscopy, facilitating atmospheric characterization. However, it remains unknown whether their host stars' highly variable extreme-UV radiation environments allow atmospheres to persist. With JWST, we have begun to determine whether or not the most favorable rocky worlds orbiting M dwarfs have detectable atmospheres. Here, we present a 2.8–5.2 μm JWST NIRSpec/G395H transmission spectrum of the warm (700 K, 40.3× Earth's insolation) super-Earth GJ 486b (1.3 R⊕ and 3.0 M⊕). The measured spectrum from our two transits of GJ 486b deviates from a flat line at 2.2σ − 3.3σ, based on three independent reductions. Through a combination of forward and retrieval models, we determine that GJ 486b either has a water-rich atmosphere (with the most stringent constraint on the retrieved water abundance of H2O > 10% to 2σ) or the transmission spectrum is contaminated by water present in cool unocculted starspots. We also find that the measured stellar spectrum is best fit by a stellar model with cool starspots and hot faculae. While both retrieval scenarios provide equal quality fits (${\chi }_{\nu }^{2}=1.0$) to our NIRSpec/G395H observations, shorter wavelength observations can break this degeneracy and reveal if GJ 486b sustains a water-rich atmosphere

The kinematic signature of the Galactic warp in Gaia DR1 : I. the H ipparcos subsample

Reproduced with permission from Astronomy & Astrophysics, © 2017 ESO.Context. The mechanism responsible for the warp of our Galaxy, as well as its dynamical nature, continues to remain unknown. With the advent of high precision astrometry, new horizons have been opened for detecting the kinematics associated with the warp and for constraining possible warp formation scenarios for the Milky Way. Aims. The aim of this contribution is to establish whether the first Gaia data release (DR1) shows significant evidence of the kinematic signature expected from a long-lived Galactic warp in the kinematics of distant OB stars. As the first paper in a series, we present our approach for analyzing the proper motions and apply it to the subsample of Hipparcos stars. Methods. We select a sample of 989 distant spectroscopically-identified OB stars from the new reduction of Hipparcos, of which 758 are also in the first Gaia data release (DR1), covering distances from 0.5 to 3 kpc from the Sun. We develop a model of the spatial distribution and kinematics of the OB stars from which we produce the probability distribution functions of the proper motions, with and without the systematic motions expected from a long-lived warp. A likelihood analysis is used to compare the expectations of the models with the observed proper motions from both Hipparcos and Gaia DR1. Results. We find that the proper motions of the nearby OB stars are consistent with the signature of a kinematic warp, while those of the more distant stars (parallax <1 mas) are not. Conclusions. The kinematics of our sample of young OB stars suggests that systematic vertical motions in the disk cannot be explained by a simple model of a stable long-lived warp. The warp of the Milky Way may either be a transient feature, or additional phenomena are acting on the gaseous component of the Milky Way, causing systematic vertical motions that are masking the expected warp signal. A larger and deeper sample of stars with Gaia astrometry will be needed to constrain the dynamical nature of the Galactic warp.Peer reviewe

Right ventricular dyssynchrony in patients with pulmonary hypertension is associated with disease severity and functional class

BACKGROUND: Abnormalities in right ventricular function are known to occur in patients with pulmonary arterial hypertension. OBJECTIVE: Test the hypothesis that chronic elevation in pulmonary artery systolic pressure delays mechanical activation of the right ventricle, termed dyssynchrony, and is associated with both symptoms and right ventricular dysfunction. METHODS: Fifty-two patients (mean age 46 ± 15 years, 24 patients with chronic pulmonary hypertension) were prospectively evaluated using several echocardiographic parameters to assess right ventricular size and function. In addition, tissue Doppler imaging was also obtained to assess longitudinal strain of the right ventricular wall, interventricular septum, and lateral wall of the left ventricle and examined with regards to right ventricular size and function as well as clinical variables. RESULTS: In this study, patients with chronic pulmonary hypertension had statistically different right ventricular fractional area change (35 ± 13 percent), right ventricular end-systolic area (21 ± 10 cm(2)), right ventricular Myocardial Performance Index (0.72 ± 0.34), and Eccentricity Index (1.34 ± 0.37) than individuals without pulmonary hypertension (51 ± 5 percent, 9 ± 2 cm(2), 0.27 ± 0.09, and 0.97 ± 0.06, p < 0.005, respectively). Furthermore, peak longitudinal right ventricular wall strain in chronic pulmonary hypertension was also different -20.8 ± 9.0 percent versus -28.0 ± 4.1 percent, p < 0.01). Right ventricular dyssynchrony correlated very well with right ventricular end-systolic area (r = 0.79, p < 0.001) and Eccentricity Index (r = 0.83, p < 0.001). Furthermore, right ventricular dyssynchrony correlates with pulmonary hypertension severity index (p < 0.0001), World Health Organization class (p < 0.0001), and number of hospitalizations (p < 0.0001). CONCLUSION: Lower peak longitudinal right ventricular wall strain and significantly delayed time-to-peak strain values, consistent with right ventricular dyssynchrony, were found in a small heterogeneous group of patients with chronic pulmonary hypertension when compared to individuals without pulmonary hypertension. Furthermore, right ventricular dyssynchrony was associated with disease severity and compromised functional class

Early and late skin reactions to radiotherapy for breast cancer and their correlation with radiation-induced DNA damage in lymphocytes

INTRODUCTION: Radiotherapy outcomes might be further improved by a greater understanding of the individual variations in normal tissue reactions that determine tolerance. Most published studies on radiation toxicity have been performed retrospectively. Our prospective study was launched in 1996 to measure the in vitro radiosensitivity of peripheral blood lymphocytes before treatment with radical radiotherapy in patients with breast cancer, and to assess the early and the late radiation skin side effects in the same group of patients. We prospectively recruited consecutive breast cancer patients receiving radiation therapy after breast surgery. To evaluate whether early and late side effects of radiotherapy can be predicted by the assay, a study was conducted of the association between the results of in vitro radiosensitivity tests and acute and late adverse radiation effects. METHODS: Intrinsic molecular radiosensitivity was measured by using an initial radiation-induced DNA damage assay on lymphocytes obtained from breast cancer patients before radiotherapy. Acute reactions were assessed in 108 of these patients on the last treatment day. Late morbidity was assessed after 7 years of follow-up in some of these patients. The Radiation Therapy Oncology Group (RTOG) morbidity score system was used for both assessments. RESULTS: Radiosensitivity values obtained using the in vitro test showed no relation with the acute or late adverse skin reactions observed. There was no evidence of a relation between acute and late normal tissue reactions assessed in the same patients. A positive relation was found between the treatment volume and both early and late side effects. CONCLUSION: After radiation treatment, a number of cells containing major changes can have a long survival and disappear very slowly, becoming a chronic focus of immunological system stimulation. This stimulation can produce, in a stochastic manner, late radiation-related adverse effects of varying severity. Further research is warranted to identify the major determinants of normal tissue radiation response to make it possible to individualize treatments and improve the outcome of radiotherapy in cancer patients

Influence of the length of hospitalisation in post-discharge outcomes in patients with acute heart failure: Results of the LOHRCA study

Objective: To investigate the relationship between length of hospitalisation (LOH) and post-discharge outcomes in acute heart failure (AHF) patients and to ascertain whether there are different patterns according to department of initial hospitalisation. Methods: Consecutive AHF patients hospitalised in 41 Spanish centres were grouped based on the LOH (15 days). Outcomes were defined as 90-day post-discharge all-cause mortality, AHF readmissions, and the combination of both. Hazard ratios (HRs), adjusted by chronic conditions and severity of decompensation, were calculated for groups with LOH >6 days vs. LOH <6 days (reference), and stratified by hospitalisation in cardiology, internal medicine, geriatrics, or short-stay units. Results: We included 8563 patients (mean age: 80 (SD = 10) years, 55.5% women), with a median LOH of 7 days (IQR 4–11): 2934 (34.3%) had a LOH 15 days. The 90-day post-discharge mortality was 11.4%, readmission 32.2%, and combined endpoint 37.4%. Mortality was increased by 36.5% (95%CI = 13.0–64.9) when LOH was 11–15 days, and by 72.0% (95%CI = 42.6–107.5) when >15 days. Conversely, no differences were found in readmission risk, and the combined endpoint only increased 21.6% (95%CI = 8.4–36.4) for LOH >15 days. Stratified analysis by hospitalisation departments rendered similar post-discharge outcomes, with all exhibiting increased mortality for LOH >15 days and no significant increments in readmission risk. Conclusions: Short hospitalisations are not associated with worse outcomes. While post-discharge readmissions are not affected by LOH, mortality risk increases as the LOH lengthens. These findings were similar across hospitalisation departments

Conjugation of a Ru(II) Arene Complex to Neomycin or to Guanidinoneomycin Leads to Compounds with Differential Cytotoxicities and Accumulation between Cancer and Normal Cells

A straightforward methodology for the synthesis of conjugates between a cytotoxic organometallic ruthenium(II) complex and amino- and guanidinoglycosides, as potential RNA-targeted anticancer compounds, is described. Under microwave irradiation, the imidazole ligand incorporated on the aminoglycoside moiety (neamine or neomycin) was found to replace one triphenylphosphine ligand from the ruthenium precursor [(η6-p-cym)RuCl(PPh3)2]+, allowing the assembly of the target conjugates. The guanidinylated analogue was easily prepared from the neomycin-ruthenium conjugate by reaction with N,N′-di-Boc-N″-triflylguanidine, a powerful guanidinylating reagent that was compatible with the integrity of the metal complex. All conjugates were purified by semipreparative high-performance liquid chromatography (HPLC) and characterized by electrospray ionization (ESI) and matrix-assisted laser desorption-ionization time-of-flight (MALDI-TOF) mass spectrometry (MS) and NMR spectroscopy. The cytotoxicity of the compounds was tested in MCF-7 (breast) and DU-145 (prostate) human cancer cells, as well as in the normal HEK293 (Human Embryonic Kidney) cell line, revealing a dependence on the nature of the glycoside moiety and the type of cell (cancer or healthy). Indeed, the neomycin-ruthenium conjugate (2) displayed moderate antiproliferative activity in both cancer cell lines (IC50 ≈ 80 μM), whereas the neamine conjugate (4) was inactive (IC50 ≈ 200 μM). However, the guanidinylated analogue of the neomycin-ruthenium conjugate (3) required much lower concentrations than the parent conjugate for equal effect (IC50 = 7.17 μM in DU-145 and IC50 = 11.33 μM in MCF-7). Although the same ranking in antiproliferative activity was found in the nontumorigenic cell line (3 2 > 4), IC50 values indicate that aminoglycoside-containing conjugates are about 2-fold more cytotoxic in normal cells (e.g., IC50 = 49.4 μM for 2) than in cancer cells, whereas an opposite tendency was found with the guanidinylated conjugate, since its cytotoxicity in the normal cell line (IC50 = 12.75 μM for 3) was similar or even lower than that found in MCF-7 and DU-145 cancer cell lines, respectively. Cell uptake studies performed by ICP-MS with conjugates 2 and 3 revealed that guanidinylation of the neomycin moiety had a positive effect on accumulation (about 3-fold higher in DU-145 and 4-fold higher in HEK293), which correlates well with the higher antiproliferative activity of 3. Interestingly, despite the slightly higher accumulation in the normal cell than in the cancer cell line (about 1.4-fold), guanidinoneomycin-ruthenium conjugate (3) was more cytotoxic to cancer cells (about 1.8-fold), whereas the opposite tendency applied for neomycin-ruthenium conjugate (2). Such differences in cytotoxic activity and cellular accumulation between cancer and normal cells open the way to the creation of more selective, less toxic anticancer metallodrugs by conjugating cytotoxic metal-based complexes such as ruthenium(II) arene derivatives to guanidinoglycosides