To evaluate the impact of COVID-19 on clinical and surgical practice, educational activities, health and lifestyle behavior of Brazilian urology residents.
A web-based survey was sent to 468 ...Brazilian urology residents from postgraduate years (PGY) 3 to 5 to collect data on clinical practice and training after 4 months of COVID-19. We also assessed health-related and behavior changes, rate of infection by SARS-CoV-2, deployment to the front line of COVID-19, residents' concerns, and access to personal protective equipment (PPE).
Massive reductions in elective and emergency patient consultations, diagnostic procedures and surgeries were reported across the country, affecting PGY 3 to 5 alike. Most in-person educational activities were abolished. The median damage to the urological training expected for 2020 was 6.0 3.4 -7.7, on a scale from 0 to 10, with senior residents estimating a greater damage (P < 0.001). Educational interventions developed included online case-based discussions, subspeciality conferences and lectures, and grand rounds. Most senior residents favored extending residency to compensate for training loss and most younger residents favored no additional training (p< 0.001). Modifications in health and lifestyle included weight gain (43.8%), reduced physical activity (68.6%), increased alcoholic intake (44.9%) and cigarette consumption (53.6%), worsening of sexual life (25.2%) and feelings of sadness or depression (48,2%). Almost half were summoned to work on the COVID-19 front-line and 24.4% had COVID-19. Most residents had inadequate training to deal with COVID-19 patients and most reported a shortage of PPE. Residents' concerns included the risk of contaminating family members, being away from residency program, developing severe COVID-19 and overloading colleagues.
COVID-19 had a massive impact in Brazilian urology residents´ training, health and lifestyle behavior, which may reflect what happened in other medical specialties. Studies should confirm these findings to help developing strategies to mitigate residents' losses.
Multifunctional core@shell nanoparticles have been synthesized in this paper through 3 stages: NiFe2O4 nanoparticles by microwave irradiation using Pedalium murex leaf extract as a fuel, core@shell ...NiFe2O4@TiO2 nanoparticles by sol-gel, and NiFe2O4@TiO2@rGO by sol-gel using preprepared reduced graphene oxide obtained by modified Hummer’s method. XRD analysis confirmed the presence of both cubic NiFe2O4 spinel and tetragonal TiO2 rutile phases, while Raman spectroscopy analysis displays both D and G bands (ID/IG = 1.04) associated with rGO. Morphological observations by HRTEM reveal a core-shell nanostructure formed by NiFe2O4 core as confirmed by SAED with subsequent thin layers of TiO2 and rGO. Magnetic measurements show a ferromagnetic behavior, where the saturation magnetization drops drastically from 45 emu/g for NiFe2O4 to 15 emu/g after TiO2 and rGO nonmagnetic bilayers coating. The as-fabricated multifunctional core@shell nanostructures demonstrate tunable self-heating characteristics: rise of temperature and specific absorption rate in the range of ΔT = 3–10°C and SAR = 3–58 W/g, respectively. This effectiveness is much close to the threshold temperature of hyperthermia (45°C), and the zones of inhibition show the better effective antibacterial activity of NTG against various Gram-positive and Gram-negative bacterial strains besides simultaneous good efficient, stable, and removable sonophotocatalyst toward the TC degradation.
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FZAB, GIS, IJS, IZUM, KILJ, NLZOH, NUK, OILJ, PILJ, PNG, SAZU, SBCE, SBMB, UL, UM, UPUK
In the present and accompanying papers we explicitly construct the on-shell supersymmetric component actions for 3-branes moving in D = 6 and D = 8 within the nonlinear realizations framework. In the ...first paper we apply our scheme to construct the action of supersymmetric 3-brane in D = 6. It turns out that all ingredients entering the component action can be obtained almost algorithmically by using the nonlinear realizations approach. Within this approach, properly adapted to the construction of the on-shell component actions, we pay much attention to broken supersymmetry. Doing so, we were able to write the action in terms of purely geometric objects (vielbeins and covariant derivatives of the physical bosonic components), covariant with respect to broken supersymmetry. It turns out that all terms of the higher orders in the fermions are hidden inside these covariant derivatives and vielbeins. Moreover, the main part of the component action just mimics its bosonic cousin in which the ordinary space-time derivatives and the bosonic worldvolume are replaced by their covariant supersymmetric analogs. The Wess-Zumino term in the action, which does not exist in the bosonic case, can be also easily constructed in terms of reduced Cartan forms. Keeping the broken supersymmetry almost explicit, one may write the ansatz for the component action, fully defined up to two constant parameters. The role of the unbroken supersymmetry is just to fix these parameters.
We evaluate the fermion condensate and the expectation values of the charge and current densities for a massive fermionic field in (
2
+
1
)-dimensional conical spacetime with a magnetic flux located ...at the cone apex. The consideration is done for both irreducible representations of the Clifford algebra. The expectation values are decomposed into the vacuum expectation values and contributions coming from particles and antiparticles. All these contributions are periodic functions of the magnetic flux with the period equal to the flux quantum. Related to the non-invariance of the model under the parity and time-reversal transformations, the fermion condensate and the charge density have indefinite parity with respect to the change of the signs of the magnetic flux and chemical potential. The expectation value of the radial current density vanishes. The azimuthal current density is the same for both the irreducible representations of the Clifford algebra. It is an odd function of the magnetic flux and an even function of the chemical potential. The behavior of the expectation values in various asymptotic regions of the parameters are discussed in detail. In particular, we show that for points near the cone apex the vacuum parts dominate. For a massless field with zero chemical potential the fermion condensate and charge density vanish. Simple expressions are derived for the part in the total charge induced by the planar angle deficit and magnetic flux. Combining the results for separate irreducible representations, we also consider the fermion condensate, charge and current densities in parity and time-reversal symmetric models. Possible applications to graphitic nanocones are discussed.
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DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
A
bstract
We argue the conjecture that the on-shell component super particle actions have a universal form, in which the physical fermions enter the action through the ein-bein and the space-time ...derivatives of the matter fields, only. We explicitly constructed the actions for the super particles in
D
= 3 realizing the
N
= 4·2
k
→
N
= 2·2
k
pattern of supersymmetry breaking, and in
D
= 5 with the
N
= 16 supersymmetry broken down to the
N
= 8 one. All constructed actions have indeed a universal form, confirming our conjecture. Our construction is strictly based on the assumption that in the system we have one half breaking of the global supersymmetry, and on the very special choice of the superspace coordinates and component fields.
Quantum interference effects in rings provide suitable means for controlling spin at mesoscopic scales. Here we apply such a control mechanism to the spin dependent transport in a ballistic ...quasi-one-dimensional ring patterned in two-dimensional electron gases (2DEGs). The study is essentially based on the natural spin-orbit (SO) interactions, one arising from the laterally confining electric field (beta term) and the other due to the quantum well potential that confines electrons in the 2DEG (conventional Rashba SO interaction or alpha term). We focus on single-channel transport and solve analytically for the spin polarization of the current. As an important consequence of the presence of spin splitting, we find the occurrence of spin dependent current oscillations.
Investigation of the complex structure based on the graphene monolayer and the twisted BN monolayer was carried out. Sharp variations in the electronic structure during the hydrogen adsorption at low ...concentration were observed. Upon increasing the hydrogen concentration on the structure surfaces more impurity levels were observed due to the addition of the hydrogen atoms without any dependence on the position of hydrogen atoms on graphene and BN surfaces. An investigation of the dependence of the band gap on the hydrogen concentration on the Moiré surface was made. Upon increasing the hydrogen concentration the value of the band gap increased up to 0.5 eV.
Investigation of the complex structure based on the graphene monolayer and the twisted BN monolayer was carried out.
We evaluate the Wightman function, the mean field squared and the vacuum expectation value of the energy–momentum tensor for a scalar field with the Robin boundary condition on a spherical shell in ...the background of a constant negative curvature space. For the coefficient in the boundary condition there is a critical value above which the scalar vacuum becomes unstable. In both the interior and the exterior regions, the vacuum expectation values are decomposed into the boundary-free and sphere-induced contributions. For the latter, rapidly convergent integral representations are provided. In the region inside the sphere, the eigenvalues are expressed in terms of the zeros of the combination of the associated Legendre function and its derivative and the decomposition is achieved by making use of the Abel–Plana type summation formula for the series over these zeros. The sphere-induced contribution to the vacuum expectation value of the field squared is negative for the Dirichlet boundary condition and positive for the Neumann one. At distances from the sphere larger than the curvature scale of the background space the suppression of the vacuum fluctuations in the gravitational field corresponding to the negative curvature space is stronger compared with the case of the Minkowskian bulk. In particular, the decay of the vacuum expectation values with the distance is exponential for both massive and massless fields. The corresponding results are generalized for spaces with spherical bubbles and for cosmological models with negative curvature spaces.
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This work explores the role of thermodynamic fluctuations in the two parameter Hawking radiating black hole configurations. The system is characterized by an ensemble of arbitrary mass and radiation ...frequency of the black holes. In the due course of the Hawking radiations, we find that the intrinsic geometric description exhibits an intriguing set of exact pair correction functions and global correlation lengths. We investigate the nature of the constant amplitude radiation and find that it’s not stable under fluctuations of the mass and frequency. Subsequently, the consideration of the York model decreasing amplitude radiation demonstrates that thermodynamic fluctuations are globally stable in the small frequency region. In connection with quantum gravity refinements, we take an account of the logarithmic correction into the constant amplitude and York amplitude over the Hawking radiation. In both considerations, we notice that the nature of the possible parametric fluctuations may precisely be ascertained without any approximation. In the frequency domain
w
∈ (0, ∞), we observe that both the local and the global thermodynamic fluctuations of the radiation energy flux are stable in the s-channel. The intrinsic geometry exemplifies a definite stability character to the thermodynamic fluctuations, and up to finitely many topological defects on the parametric surface, the notion remains almost the same for both the constant amplitude and the York model. The Gaussian fluctuations over equilibrium radiation energy flux and fluctuating horizon configurations accomplish a well-defined, non-degenerate, curved and regular intrinsic Riemannian manifolds, for all the physically admissible domains of the radiation parameters.
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EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, KILJ, KISLJ, MFDPS, NUK, OILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
The recent ability to manipulate graphene-like structures at the atomic scale is opening up new challenges in electronics and photonics, with a key focus on the bulk and edges of the systems, which ...generate peculiar and interfering charge density oscillations, quantized as plasmons. These quasiparticles are here scrutinized in planar periodic distributions (two-dimensional arrays) of parallel and atomically wide graphene nanoribbons. Time-dependent density functional theory is used, with a specifically developed adjustment on the random phase approximation, suitable for two-dimensional materials. Several extrinsic conditions (for doped or gated nanoribbon arrays) are simulated to characterize the propagation and interplay of the bulk and edge plasmons, at far infrared to visible energies, and over a broad range of momentum transfers. The main technological interest is on the bulk mode, which is dominant and propagates undamped, at energies below the band gap of the intrinsic systems. On the other hand, the edge mode is always well defined at energies above the band gap, and highly dependent on the band gap value, though it decays via electron-hole excitations between the first valence and conduction bands. Particular attention is paid to the interaction or overlap region of the two plasmons, explaining its sensitivity to induced Fermi level shifting, transferred momentum, ribbon type, and geometry, with the inclusion of many-body, GW-like effects. More importantly, the lower-terahertz behavior of the bulk plasmon is explored, highlighting the limits of available non–ab initio approaches, suitable for stripes of graphene being tenths of nanometers wide. Then, an effective model is derived from the ab initio framework, which reasonably accounts for the two-plasmon response of the studied, ultranarrow nanoribbon systems, at small momentum transfers. The range of applicability of the same derivation procedure may be extended to more complex nanoribbon heterostructures available for synthesis, which emphasizes the need for an ab initio guide to a reliable design of nanoplasmonic devices.
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