Ferroelectricity and multiferroicity in anti-Ruddlesden-Popper structures.

Combining ferroelectricity with other properties such as visible light absorption or long-range magnetic order requires the discovery of new families of ferroelectric materials. Here, through the analysis of a high-throughput database of phonon band structures, we identify a structural family of anti-Ruddlesden-Popper phases [Formula: see text]O (A=Ca, Sr, Ba, Eu, X=Sb, P, As, Bi) showing ferroelectric and antiferroelectric behaviors. The discovered ferroelectrics belong to the new class of hyperferroelectrics that polarize even under open-circuit boundary conditions. The polar distortion involves the movement of O anions against apical A cations and is driven by geometric effects resulting from internal chemical strains. Within this structural family, we show that [Formula: see text]O combines coupled ferromagnetic and ferroelectric order at the same atomic site, a very rare occurrence in materials physics.

Electron-Phonon beyond Fröhlich: Dynamical Quadrupoles in Polar and Covalent Solids.

We include the treatment of quadrupolar fields beyond the Fröhlich interaction in the first-principles electron-phonon vertex in semiconductors. Such quadrupolar fields induce long-range interactions that have to be taken into account for accurate physical results. We apply our formalism to Si (nonpolar), GaAs, and GaP (polar) and demonstrate that electron mobilities show large errors if dynamical quadrupoles are not properly treated.

Plasma levels of soluble HLA-G and cytokines in papillary thyroid carcinoma before and after thyroidectomy.

BACKGROUND: Increasing evidence shows that chronic inflammation plays an important role in thyroid tumorigenesis. Cytokines as central mediators in inflammatory microenvironment can present both pro-tumour and anti-tumour effects and cytokine release may be influenced by soluble HLA-G (sHLA-G), an immune checkpoint molecule whose expression can also be induced by certain cytokines. AIM: To understand the role of these soluble factors in papillary thyroid cancer (PTC). METHODS: We evaluated plasma levels of sHLA-G and of 13 cytokines using ELISA and flow cytometry, respectively, in PTC patients at two time points: pre- and post-thyroidectomy; and control subjects. RESULTS: Compared with controls, IL-6 levels were increased, while IL-1ß, IFN-α and TGF-ß1 levels were decreased in pre-thyroidectomy PTC patients. IFN-α and TGF-ß1 efficiently discriminated patients from controls and were associated with extrathyroidal extension and lymph node metastasis, respectively. In addition, TNF and IL-13 were associated with male gender, lymph node metastasis and Hashimoto thyroiditis, and sHLA-G with tumour invasion. Compared with pre-thyroidectomy, IL-4, IL-10, TNF, IFN-α and TGF-ß1 levels were increased in post-thyroidectomy. CONCLUSION: There are significant changes in the cytokine profile after surgical removal of the thyroid tumour, and IFN-α e TGF-ß1 showed to be promising cytokines for discriminating PTC patients from controls. We also found that different cytokines are associated with clinicohistopathological characteristics of PTC related to poor prognosis, suggesting that cytokines seem to play an important role in PTC development and management.

Strongly Coupled Coherent Phonons in Single-Layer MoS2.

We present a transient absorption setup combining broadband detection over the visible-UV range with high temporal resolution (∼20 fs) which is ideally suited to trigger and detect vibrational coherences in different classes of materials. We generate and detect coherent phonons (CPs) in single-layer (1L)-MoS2, as a representative semiconducting 1L-transition metal dichalcogenide (TMD), where the confined dynamical interaction between excitons and phonons is unexplored. The coherent oscillatory motion of the out-of-plane A'1 phonons, triggered by the ultrashort laser pulses, dynamically modulates the excitonic resonances on a time scale of few tens of fs. We observe an enhancement by almost 2 orders of magnitude of the CP amplitude when detected in resonance with the C exciton peak, combined with a resonant enhancement of CP generation efficiency. Ab initio calculations of the change in the 1L-MoS2 band structure induced by the A'1 phonon displacement confirm a strong coupling with the C exciton. The resonant behavior of the CP amplitude follows the same spectral profile of the calculated Raman susceptibility tensor. These results explain the CP generation process in 1L-TMDs and demonstrate that CP excitation in 1L-MoS2 can be described as a Raman-like scattering process.

ABINIT: Overview and focus on selected capabilities.

abinit is probably the first electronic-structure package to have been released under an open-source license about 20 years ago. It implements density functional theory, density-functional perturbation theory (DFPT), many-body perturbation theory (GW approximation and Bethe-Salpeter equation), and more specific or advanced formalisms, such as dynamical mean-field theory (DMFT) and the "temperature-dependent effective potential" approach for anharmonic effects. Relying on planewaves for the representation of wavefunctions, density, and other space-dependent quantities, with pseudopotentials or projector-augmented waves (PAWs), it is well suited for the study of periodic materials, although nanostructures and molecules can be treated with the supercell technique. The present article starts with a brief description of the project, a summary of the theories upon which abinit relies, and a list of the associated capabilities. It then focuses on selected capabilities that might not be present in the majority of electronic structure packages either among planewave codes or, in general, treatment of strongly correlated materials using DMFT; materials under finite electric fields; properties at nuclei (electric field gradient, Mössbauer shifts, and orbital magnetization); positron annihilation; Raman intensities and electro-optic effect; and DFPT calculations of response to strain perturbation (elastic constants and piezoelectricity), spatial dispersion (flexoelectricity), electronic mobility, temperature dependence of the gap, and spin-magnetic-field perturbation. The abinit DFPT implementation is very general, including systems with van der Waals interaction or with noncollinear magnetism. Community projects are also described: generation of pseudopotential and PAW datasets, high-throughput calculations (databases of phonon band structure, second-harmonic generation, and GW computations of bandgaps), and the library libpaw. abinit has strong links with many other software projects that are briefly mentioned.

Exciton-Phonon Coupling in the Ultraviolet Absorption and Emission Spectra of Bulk Hexagonal Boron Nitride.

We present an ab initio method to calculate phonon-assisted absorption and emission spectra in the presence of strong excitonic effects. We apply the method to bulk hexagonal BN, which has an indirect band gap and is known for its strong luminescence in the UV range. We first analyze the excitons at the wave vector q[over ¯] of the indirect gap. The coupling of these excitons with the various phonon modes at q[over ¯] is expressed in terms of a product of the mean square displacement of the atoms and the second derivative of the optical response function with respect to atomic displacement along the phonon eigenvectors. The derivatives are calculated numerically with a finite difference scheme in a supercell commensurate with q[over ¯]. We use detailed balance arguments to obtain the intensity ratio between emission and absorption processes. Our results explain recent luminescence experiments and reveal the exciton-phonon coupling channels responsible for the emission lines.

High-throughput density-functional perturbation theory phonons for inorganic materials.

The knowledge of the vibrational properties of a material is of key importance to understand physical phenomena such as thermal conductivity, superconductivity, and ferroelectricity among others. However, detailed experimental phonon spectra are available only for a limited number of materials, which hinders the large-scale analysis of vibrational properties and their derived quantities. In this work, we perform ab initio calculations of the full phonon dispersion and vibrational density of states for 1521 semiconductor compounds in the harmonic approximation based on density functional perturbation theory. The data is collected along with derived dielectric and thermodynamic properties. We present the procedure used to obtain the results, the details of the provided database and a validation based on the comparison with experimental data.

Glycemic Variability and Insulin Needs in Patients with Type 1 Diabetes Mellitus Supplemented with Vitamin D: A Pilot Study Using Continuous Glucose Monitoring System.

BACKGROUND: Recent studies suggest that glycemic variability could influence the risk of complications in Type 1 Diabetes Mellitus (T1DM). There are no data about the action of Vitamin D (VD) on glycemic variability. Our pilot study aims to evaluate glycemic variability and insulin needs in patients with T1DM supplemented with VD. METHODS: 22 Patients received doses of 4000 and 10000 IU/day of cholecalciferol for 12 weeks, according to the patient's baseline VD levels and underwent continuous glucose monitoring system. RESULTS: Correlations were found between percentage variation (Δ) of glycemia standard deviation (ΔSDG), calculated using continuous glucose monitoring, with Δ of basal (r = 0.6; p <0.01) and total insulin dose (r = 0.6; p <0.01). Correlations between VD status after supplementation and Δ of prandial (r = 0.5; p <0.05) and total insulin dose (r = 0.4; p <0.05) were found, suggesting that the dose of insulin needed by patients is lower when VD status is better. We divided patients in two subgroups: SDG improved (subgroup 1; N = 12 (55%)) and SDG worsened (subgroup 2; N = 10 (45%)). Group 1, compared to subgroup 2, required a lower insulin dose (Δbasal insulin dose = -8.0 vs. 6.3%; p <0.05) and had a lower frequency of hypoglycemia (27% vs. 64%, hypoglycemias/days evaluated; p <0.01). CONCLUSION: Our study suggests a relation between VD supplementation, improved glycemic variability, lower insulin needs and lower frequency of hypoglycemia in patients with T1DM.

Quantum Interference Effects in Resonant Raman Spectroscopy of Single- and Triple-Layer MoTe2 from First-Principles.

We present a combined experimental and theoretical study of resonant Raman spectroscopy in single- and triple-layer MoTe2. Raman intensities are computed entirely from first-principles by calculating finite differences of the dielectric susceptibility. In our analysis, we investigate the role of quantum interference effects and the electron-phonon coupling. With this method, we explain the experimentally observed intensity inversion of the A1' vibrational modes in triple-layer MoTe2 with increasing laser photon energy. Finally, we show that a quantitative comparison with experimental data requires the proper inclusion of excitonic effects.

Complete and Sustained Response with a Doublet Chemotherapy Protocol in an 81-Year-Old Patient with Metastatic Breast Cancer.

Metastatic breast cancer (MBC) entails an overall 5-year survival of approximately 25%. The choice of therapy is influenced by expression of the HER2 gene and hormone receptors, by a disease-free interval, and by age. The use of paclitaxel combined with gemcitabine (doublet protocol) has shown efficacy as first-line treatment for MBC in either initial or maintenance therapy when compared to monotherapy with paclitaxel. There is evidence showing that the doublet protocol is a good alternative to maintenance therapy in women under 50 years old. Nevertheless, there is a lack of information concerning individuals above that age. We report the case of an 81-year-old patient presenting with recurrence of MBC, with lung and skin metastases both positive for hormone receptor and negative for HER2. We implemented a therapy based on the combination of gemcitabine and paclitaxel for 12 cycles, when complete response was achieved. Currently, 16 months after this achievement, the patient is receiving maintenance treatment under the doublet protocol, presenting acceptable parameters of toxicity since the beginning of treatment, which shows satisfactory tolerability and management of chemotherapy in an elderly patient. We suggest that the maintenance treatment protocol with a doublet might be an alternative with a satisfactory response in patients with MBC.

Conhecimento de estudantes de medicina sobre o testamento vital / Knowledge of medical students regarding living wills

A terminalidade da vida levanta cada vez mais dilemas éticos. Dada a importância do tema e a recente regulamentação do testamento vital pelo Conselho Federal de Medicina, é de grande valor o conhecimento dessa problemática por parte dos futuros médicos. Assim, buscou-se aferir a compreensão dos estudantes de medicina da Universidade do Estado do Pará acerca do testamento vital e das decisões envolvendo o final da vida. O estudo qualiquantitativo descritivo e transversal entrevistou 238 estudantes por meio de questionário com 10 questões. Apenas 8% dos estudantes demonstraram ter uma noção clara sobre o significado do termo “testamento vital”. Apesar disso, após ouvirem a definição das diretivas antecipadas de vontade fornecida pelos pesquisadores, 92% deles declararam que respeitariam o previsto no testamento vital. Portanto, conclui-se que, embora boa parte dos entrevistados tenha pouco entendimento sobre o tema “testamento vital”, a grande maioria posicionou-se a favor de sua aceitação...

The end of a person’s life raises many ethical dilemmas. Recently, the Brazil’s Federal Council of Medicine approved and regulated the concept of “living will”; as a result, it is of considerable importance that doctors understand the issues that surround this matter. The aim of the present study was to evaluate the knowledge of medical students from the Pará State University, Brazil, of “living wills” and decisions involving the end of life. A cross-sectional study was performed with 238 students who answered a questionnaire of 10 questions. Only 8% of students demonstrated a clear understanding of the term “living will”. Nevertheless, when the definition of “living will” was explained to the participants of the study by the researchers, 92% of students declared that they would respect its provisions. Therefore it appears that while most respondents had a low level of understanding of the concept of “living will”, the vast majority positioned themselves in favor of accepting such a document...

La terminalidad de la vida levanta cada vez más dilemas éticos. Dada la importancia del tema y la reciente regulación del testamento vital por el Consejo Federal de Medicina del Brasil, es de gran valor el conocimiento de los futuros médicos acerca de este problema. Por lo tanto, tratamos de evaluar el conocimiento de los estudiantes de medicina de la Universidad del Estado del Pará, en Brasil, acerca del testamento vital y de las decisiones que involucran el final de la vida. La muestra del estudio cualitativo y cuantitativo descriptivo y transversal entrevistó 238 estudiantes y utilizó cuestionario con 10 preguntas. Sólo el 8% de los estudiantes han demostrado una clara comprensión sobre el término “testamento en vida”. Sin embargo, después de escuchar la definición de directrices anticipadas de voluntad proporcionada por los investigadores, el 92% del total declaró que respetarían las disposiciones del testamento vital. Por lo tanto, parece que la mayoría de los encuestados tienen un bajo nivel de comprensión del tema del “Testamento Vital”, pero la gran mayoría se ha posicionado a favor de la aceptación...

Simaroubaceae family: botany, chemical composition and biological activities

The Simaroubaceae family includes 32 genera and more than 170 species of trees and brushes of pantropical distribution. The main distribution hot spots are located at tropical areas of America, extending to Africa, Madagascar and regions of Australia bathed by the Pacific. This family is characterized by the presence of quassinoids, secondary metabolites responsible of a wide spectrum of biological activities such as antitumor, antimalarial, antiviral, insecticide, feeding deterrent, amebicide, antiparasitic and herbicidal. Although the chemical and pharmacological potential of Simaroubaceae family as well as its participation in official compendia; such as British, German, French and Brazilian pharmacopoeias, and patent registration, many of its species have not been studied yet. In order to direct further investigation to approach detailed botanical, chemical and pharmacological aspects of the Simaroubaceae, the present work reviews the information regarding the main genera of the family up to 2013.

HermesD: A High-Rate Long-Range Wireless Transmission System for Simultaneous Multichannel Neural Recording Applications.

HermesD is a high-rate, low-power wireless transmission system to aid research in neural prosthetic systems for motor disabilities and basic motor neuroscience. It is the third generation of our "Hermes systems" aimed at recording and transmitting neural activity from brain-implanted electrode arrays. This system supports the simultaneous transmission of 32 channels of broadband data sampled at 30 ks/s, 12 b/sample, using frequency-shift keying modulation on a carrier frequency adjustable from 3.7 to 4.1 GHz, with a link range extending over 20 m. The channel rate is 24 Mb/s and the bit stream includes synchronization and error detection mechanisms. The power consumption, approximately 142 mW, is low enough to allow the system to operate continuously for 33 h, using two 3.6-V/1200-mAh Li-SOCl2 batteries. The transmitter was designed using off-the-shelf components and is assembled in a stack of three 28 mm ? 28-mm boards that fit in a 38 mm ? 38 mm ? 51-mm aluminum enclosure, a significant size reduction over the initial version of HermesD. A 7-dBi circularly polarized patch antenna is used as the transmitter antenna, while on the receiver side, a 13-dBi circular horn antenna is employed. The advantages of using circularly polarized waves are analyzed and confirmed by indoor measurements. The receiver is a stand-alone device composed of several submodules and is interfaced to a computer for data acquisition and processing. It is based on the superheterodyne architecture and includes automatic frequency control that keeps it optimally tuned to the transmitter frequency. The HermesD communications performance is shown through bit-error rate measurements and eye-diagram plots. The sensitivity of the receiver is -83 dBm for a bit-error probability of 10(-9). Experimental recordings from a rhesus monkey conducting multiple tasks show a signal quality comparable to commercial acquisition systems, both in the low-frequency (local field potentials) and upper-frequency bands (action potentials) of the neural signals. This system can be easily scaled up in terms of the number of channels and data rate to accommodate future generations of Hermes systems.