To understand the complex physics of a system with strong electron-electron interactions, the ideal is to control and monitor its properties while tuning an external electric field applied to the ...system (the electric-field effect). Indeed, complete electric-field control of many-body states in strongly correlated electron systems is fundamental to the next generation of condensed matter research and devices. However, the material must be thin enough to avoid shielding of the electric field in the bulk material. Two-dimensional materials do not experience electrical screening, and their charge-carrier density can be controlled by gating. Octahedral titanium diselenide (1T-TiSe2) is a prototypical two-dimensional material that reveals a charge-density wave (CDW) and superconductivity in its phase diagram, presenting several similarities with other layered systems such as copper oxides, iron pnictides, and crystals of rare-earth elements and actinide atoms. By studying 1T-TiSe2 single crystals with thicknesses of 10 nanometres or less, encapsulated in two-dimensional layers of hexagonal boron nitride, we achieve unprecedented control over the CDW transition temperature (tuned from 170 kelvin to 40 kelvin), and over the superconductivity transition temperature (tuned from a quantum critical point at 0 kelvin up to 3 kelvin). Electrically driving TiSe2 over different ordered electronic phases allows us to study the details of the phase transitions between many-body states. Observations of periodic oscillations of magnetoresistance induced by the Little-Parks effect show that the appearance of superconductivity is directly correlated with the spatial texturing of the amplitude and phase of the superconductivity order parameter, corresponding to a two-dimensional matrix of superconductivity. We infer that this superconductivity matrix is supported by a matrix of incommensurate CDW states embedded in the commensurate CDW states. Our results show that spatially modulated electronic states are fundamental to the appearance of two-dimensional superconductivity.
Summary
During the 2011 International Pigment Cell Conference (IPCC), the Vitiligo European Taskforce (VETF) convened a consensus conference on issues of global importance for vitiligo clinical ...research. As suggested by an international panel of experts, the conference focused on four topics: classification and nomenclature; definition of stable disease; definition of Koebner’s phenomenon (KP); and ‘autoimmune vitiligo’. These topics were discussed in seven working groups representing different geographical regions. A consensus emerged that segmental vitiligo be classified separately from all other forms of vitiligo and that the term ‘vitiligo’ be used as an umbrella term for all non‐segmental forms of vitiligo, including ‘mixed vitiligo’ in which segmental and non‐segmental vitiligo are combined and which is considered a subgroup of vitiligo. Further, the conference recommends that disease stability be best assessed based on the stability of individual lesions rather than the overall stability of the disease as the latter is difficult to define precisely and reliably. The conference also endorsed the classification of KP for vitiligo as proposed by the VETF (history based, clinical observation based, or experimentally induced). Lastly, the conference agreed that ‘autoimmune vitiligo’ should not be used as a separate classification as published evidence indicates that the pathophysiology of all forms of vitiligo likely involves autoimmune or inflammatory mechanisms.
AbstractObjectiveTo determine whether tocilizumab improves clinical outcomes for patients with severe or critical coronavirus disease 2019 (covid-19).DesignRandomised, open label trial.SettingNine ...hospitals in Brazil, 8 May to 17 July 2020.ParticipantsAdults with confirmed covid-19 who were receiving supplemental oxygen or mechanical ventilation and had abnormal levels of at least two serum biomarkers (C reactive protein, D dimer, lactate dehydrogenase, or ferritin). The data monitoring committee recommended stopping the trial early, after 129 patients had been enrolled, because of an increased number of deaths at 15 days in the tocilizumab group.InterventionsTocilizumab (single intravenous infusion of 8 mg/kg) plus standard care (n=65) versus standard care alone (n=64).Main outcome measureThe primary outcome, clinical status measured at 15 days using a seven level ordinal scale, was analysed as a composite of death or mechanical ventilation because the assumption of odds proportionality was not met.ResultsA total of 129 patients were enrolled (mean age 57 (SD 14) years; 68% men) and all completed follow-up. All patients in the tocilizumab group and two in the standard care group received tocilizumab. 18 of 65 (28%) patients in the tocilizumab group and 13 of 64 (20%) in the standard care group were receiving mechanical ventilation or died at day 15 (odds ratio 1.54, 95% confidence interval 0.66 to 3.66; P=0.32). Death at 15 days occurred in 11 (17%) patients in the tocilizumab group compared with 2 (3%) in the standard care group (odds ratio 6.42, 95% confidence interval 1.59 to 43.2). Adverse events were reported in 29 of 67 (43%) patients who received tocilizumab and 21 of 62 (34%) who did not receive tocilizumab.ConclusionsIn patients with severe or critical covid-19, tocilizumab plus standard care was not superior to standard care alone in improving clinical outcomes at 15 days, and it might increase mortality.Trial registrationClinicalTrials.gov NCT04403685.
Swarm-founding wasps are endemic and common representatives of neotropical fauna and compose an interesting social tribe of vespids, presenting both complex social characteristics and uncommon traits ...for a eusocial group, such as the absence of castes with distinct morphology. The paper wasp Protonectarina sylveirae (Saussure) presents a broad distribution from Brazil, Argentina and Paraguay, occurring widespread in the Atlantic rainforest and arboreal Caatinga, being absent in the Amazon region. Given the peculiar distribution among swarm-founding wasps, an integrative approach to reconstruct the evolutionary history of P. sylveirae in a spatial-temporal framework was performed to investigate: the presence of genetic structure and its relationship with the geography, the evolution of distinct morphologic lineages and the possible historical event(s) in Neotropical region, which could explain the observed phylogeographic pattern. Individuals of P. sylveirae were obtained from populations of 16 areas throughout its distribution for DNA extraction and amplification of mitochondrial genes 12S, 16S and COI. Analysis of genetic diversity, construction of haplotype net, analysis of population structure and dating analysis of divergence time were performed. A morphometric analysis was also performed using 8 measures of the body of the adult (workers) to test if there are morphological distinction among populations. Thirty-five haplotypes were identified, most of them exclusively of a group and a high population structure was found. The possibility of genetic divergence because of isolation by distance was rejected. Morphological analysis pointed to a great uniformity in phenotypes, with only a small degree of differentiation between populations of south and the remaining. Divergence time analysis showed a Middle/Late Miocene origin, a period where an extensive marine ingression occurred in South America. Divergence of haplogroups began from the Plio/Pleistocene boundary and the last glacial maximum most likely modeled the current distribution of species, even though it was not the cause of genetic breaks.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Edge phonons in black phosphorus Ribeiro, H B; Villegas, C E P; Bahamon, D A ...
Nature communications,
07/2016, Letnik:
7, Številka:
1
Journal Article
Recenzirano
Odprti dostop
Black phosphorus has recently emerged as a new layered crystal that, due to its peculiar and anisotropic crystalline and electronic band structures, may have important applications in electronics, ...optoelectronics and photonics. Despite the fact that the edges of layered crystals host a range of singular properties whose characterization and exploitation are of utmost importance for device development, the edges of black phosphorus remain poorly characterized. In this work, the atomic structure and behaviour of phonons near different black phosphorus edges are experimentally and theoretically studied using Raman spectroscopy and density functional theory calculations. Polarized Raman results show the appearance of new modes at the edges of the sample, and their spectra depend on the atomic structure of the edges (zigzag or armchair). Theoretical simulations confirm that the new modes are due to edge phonon states that are forbidden in the bulk, and originated from the lattice termination rearrangements.
In this work, it is proposed the development a new monopole directional antenna, bioinspired in elliptical leaf, with cut by golden ratio, for 4G band application, by the use of the technique of the ...cut of the radiating element for the increasing of the antenna perimeter, being the first work to use this technique in a bioinspired antenna, promotes resonance frequency turned, and reconfiguring of the antenna parameters as bandwidth, radiation pattern and gain, with the use of the reflector near to the group plane, without the insertion of active devices as the pin diode or change in radiating element. The shape antenna is generated by Gielis formula, built in FR4 substrate, with cuts calculated by golden ratio. To compare the results of the bioinspired monopole on the elliptical sheet, a square-shaped monopole antenna was designed, simulated and measured, the structures were designed in the MATLAB software version 2015(b) and the simulations were performed in the Ansys software version 2016. In the results compared between the square monopole and the bioinspired antenna in the elliptical sheet, it can be seen that the measured bioinspired antenna, compared to the square monopole, presented a bandwidth reduction of 77.27%, a more compact structure, with a reduction of 98%, covering the wireless local area network, and long-time evolution 4G at 2.5 GHz. The proposed technique uses a reflector on the ground plane, to change the parameters of the monopole planar antenna, of omnidirectional radiation pattern to a directional, maintaining the characteristics of the broadband, half-power beamwidth great than 100°, with high current density, and similar gain of a directional antenna. From the results, it has been observed that the elliptical leaf monopole antenna shows broadband characteristics, with a half-power beamwidth of 128°, wideband, the bandwidth of 500 MHz, a gain of 6.28 dBi, a current density of 13.01 A/m
, and circular polarization.
Proposal techniques that reduce financial costs in the diagnosis and treatment of animal diseases are welcome. This work uses some machine learning techniques to classify whether or not cases of ...canine visceral leishmaniasis are present by physical examinations. For validation of the method, four machine learning models were chosen: K-nearest neighbor, Naïve Bayes, support vector machine and logistic regression models. The tests were performed on three hundred and forty dogs, using eighteen characteristics of the animal and the ELISA (enzyme-linked immunosorbent assay) serological test as validation. Logistic regression achieved the best metrics: Accuracy of 75%, sensitivity of 84%, specificity of 67%, a positive likelihood ratio of 2.53 and a negative likelihood ratio of 0.23, showing a positive relationship in the evaluation between the true positives and rejecting the cases of false negatives.
Concerted political attention has focused on reducing deforestation, and this remains the cornerstone of most biodiversity conservation strategies. However, maintaining forest cover may not reduce ...anthropogenic forest disturbances, which are rarely considered in conservation programmes. These disturbances occur both within forests, including selective logging and wildfires, and at the landscape level, through edge, area and isolation effects. Until now, the combined effect of anthropogenic disturbance on the conservation value of remnant primary forests has remained unknown, making it impossible to assess the relative importance of forest disturbance and forest loss. Here we address these knowledge gaps using a large data set of plants, birds and dung beetles (1,538, 460 and 156 species, respectively) sampled in 36 catchments in the Brazilian state of Pará. Catchments retaining more than 69–80% forest cover lost more conservation value from disturbance than from forest loss. For example, a 20% loss of primary forest, the maximum level of deforestation allowed on Amazonian properties under Brazil’s Forest Code, resulted in a 39–54% loss of conservation value: 96–171% more than expected without considering disturbance effects. We extrapolated the disturbance-mediated loss of conservation value throughout Pará, which covers 25% of the Brazilian Amazon. Although disturbed forests retained considerable conservation value compared with deforested areas, the toll of disturbance outside Pará’s strictly protected areas is equivalent to the loss of 92,000–139,000 km2 of primary forest. Even this lowest estimate is greater than the area deforested across the entire Brazilian Amazon between 2006 and 2015 (ref. 10). Species distribution models showed that both landscape and within-forest disturbances contributed to biodiversity loss, with the greatest negative effects on species of high conservation and functional value. These results demonstrate an urgent need for policy interventions that go beyond the maintenance of forest cover to safeguard the hyper-diversity of tropical forest ecosystems.
Aims
To evaluate the ability of the haloarchaeon Haloferax volcanii to produce Ag and Au nanoparticles (NPs) and to characterize the obtained material in order to find relevant properties for future ...potential applications.
Methods and Results
Nanoparticles were produced by incubating H. volcanii cells with the corresponding metal salt. In the presence of precursor salts, cultures evidenced a colour change associated to the formation of metallic nanostructures with plasmonic bands located in the visible range of the spectrum. X‐ray fluorescence analysis confirmed the presence of Ag and Au in the NPs which were spherical, with average sizes of 25 nmol l−1 (Ag) and 10 nmol l−1 (Au), as determined by electronic microscopy. Fourier transformed infrared spectroscopy indicated that both types of NPs showed a stable protein capping. Ag NPs evidenced antibacterial activity and Au NPs improved the specificity of polymerase chain reaction reactions. Au and Ag NPs were able to reduce 4‐nitrophenol when incubated with NaBH4.
Conclusions
Haloferax volcanii is able to synthesize metallic NPs with interesting properties for technological applications.
Significance and Impact of the Study
Our data demonstrate the ability of H. volcanii to synthesize metal NPs and constitutes a solid starting point to deepen the study and explore novel applications.
Introduction
A considerable number of patients experience some long-term weight regain after bariatric surgery. Body contouring surgery (BCS) is thought to strengthen post-bariatric surgery patients ...in their weight control and maintenance of achieved improvements in comorbidities.
Objectives
To examine the impact of BCS on long-term weight control and comorbidities after bariatric surgery.
Methods
We performed a retrospective study in a prospective database. All patients who underwent primary Roux-en-Y gastric bypass (RYGB) and presented for preoperative consultation of BCS in the same hospital were included in the study. Linear and logistic mixed-effect model analyses were used to evaluate the longitudinal relationships between patients who were accepted or rejected for BCS and their weight loss outcomes or changes in comorbidities.
Results
Of the 1150 patients who underwent primary RYGB between January 2010 and December 2014, 258 patients (22.4%) presented for preoperative consultation of BCS. Of these patients, 126 patients eventually underwent BCS (48.8%). Patients who were accepted for BCS demonstrated significant better ∆body mass index (BMI) on average over time (− 1.31 kg/m
2
/year, 95% confidence interval (CI) −2.52 − −0.10,
p
= 0.034) and percent total weight loss (%TWL) was significantly different at 36 months (5.79, 95%CI 1.22 – 10.37,
p
= 0.013) and 48 months (6.78, 95%CI 0.93 – 12.63,
p
= 0.023) after body contouring consultation. Patients who were accepted or rejected did not differ significantly in the maintenance of achieved improvements in comorbidities.
Conclusion
BCS could not be associated with the maintenance of achieved improvements in comorbidities after bariatric surgery, whereas it could be associated with improved weight loss maintenance at 36 and 48 months after body contouring consultation. This association should be further explored in a large longitudinal study.
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