ABSTRACT
We introduce a new prescription for the evolution of globular clusters (GCs) during the initial embedded gas phase into a Monte Carlo method. With a simplified version of the Monte Carlo ...MOCCA code embedded in the amuse framework, we study the survival of GCs after the removal of primordial gas. We first test our code and show that our results for the evolution of mass and Lagrangian radii are in good agreement with those obtained with N-body simulations. The Monte Carlo code enables a more rapid exploration of the evolution of systems with a larger number of stars than N-body simulations. We have carried out a new survey of simulations to explore the evolution of globular clusters with up to N = 500 000 stars for a range of different star formation efficiencies and half-mass radii. Our study shows the range of initial conditions leading to the clusters’ dissolution and those for which the clusters can survive this early evolutionary phase.
We established an international consortium to review and discuss relevant clinical evidence in order to develop expert consensus statements related to cancer management during the severe acute ...respiratory syndrome coronavirus 2-related disease (COVID-19) pandemic. The steering committee prepared 10 working packages addressing significant clinical questions from diagnosis to surgery. During a virtual consensus meeting of 62 global experts and one patient advocate, led by the European Society for Medical Oncology, statements were discussed, amended and voted upon. When consensus could not be reached, the panel revised statements until a consensus was reached. Overall, the expert panel agreed on 28 consensus statements that can be used to overcome many of the clinical and technical areas of uncertainty ranging from diagnosis to therapeutic planning and treatment during the COVID-19 pandemic.
Forest provides ecosystem services (ES) for community well being through local livelihoods. Tropical sal forest of West Bengal, India is not an exception, rather the tribal communities in forest ...fringe villages rely on it. The present study aims to quantify and estimate the values of provisioning and regulating ES and their contribution towards local livelihoods. The study revealed variation in provisional services quantity among the villages with highest percentage contribution by fodder and highest monetary value for fuelwood. Estimated monetary value of provisioning ES was INR 1859.00 person⁻¹ year⁻¹. Regulatory services that included carbon stock estimation (68.71 tC ha⁻¹) have potential to sequester 252.17 tCO₂ ha⁻¹. Estimated monetary value of trees under regulatory services was INR 25,0221.00 ha⁻¹. The stakeholder perception of such services showed positive responses, supporting the results of ES estimation and valuation. Income from forest products contributed 24% of total household income. Total economic value of ES in the study area was INR 13.052 billion year⁻¹. Thus, studies are required for better understanding of the ES contribution to human well-being of a region to develop sustainable livelihood framework and proper forest management strategies for biodiversity conservation.
Atomically sharp oxide heterostructures exhibit a range of novel physical phenomena that are absent in the parent compounds. A prominent example is the appearance of highly conducting and ...superconducting states at the interface between LaAlO3 and SrTiO3. Here we report an emergent phenomenon at the LaMnO3/SrTiO3 interface where an antiferromagnetic Mott insulator abruptly transforms into a nanoscale inhomogeneous magnetic state. Upon increasing the thickness of LaMnO3, our scanning nanoSQUID-on-tip microscopy shows spontaneous formation of isolated magnetic nanoislands, which display thermally activated moment reversals in response to an in-plane magnetic field. The observed superparamagnetic state manifests the emergence of thermodynamic electronic phase separation in which metallic ferromagnetic islands nucleate in an insulating antiferromagnetic matrix. We derive a model that captures the sharp onset and the thickness dependence of the magnetization. Our model suggests that a nearby superparamagnetic-ferromagnetic transition can be gate tuned, holding potential for applications in magnetic storage and spintronics.
Here we present an overview of some of our recent experimental investigation on the high conducting topologically protected surface state properties of a 3D topological insulator (TI), Bi
2
Se
3
, in ...both bulk and single-crystals form. Selenium (Se) vacancies in Bi
2
Se
3
are natural bulk charge dopants, hence these vacancies act as non-magnetic defects in these materials. We use Bi
2
Se
3
material as a prototype of a 3D TI) material with the disorder, for exploring the effects of non-magnetic disorder on the topological conducting surface states. Using a sensitive non-contact mutual inductance-based measurement technique, we identify distinct signatures of surface and bulk contributions to electrical conductivity in a TI Bi
2
Se
3
. We show a temperature-dependent transformation from surface to bulk dominated electrical conductivity and unravel the unusual resurfacing of a surface-dominated electrical conductivity at high temperatures. We show that the surface to bulk conductivity transformation is related to a unique activation energy scale Δ in the range of tens of meV, which is smaller than the bulk-insulating gap in Bi
2
Se
3
. This gap, we believe is related to a defect state created by the charge dopant Se vacancies in Bi
2
Se
3
. We also see interesting effects related to disorder-related coupling of the surface states. The Se vacancies which dope the bulk of the Bi
2
Se
3
crystal lead to an unusual inductive-type coupling of the high conducting 2D-like surface states. The coupling leads to a critical thickness feature in bulk TI crystal, which is distinct from the direct coupling limit in TI’s. We find that if the thickness of the Bi
2
Se
3
crystal exceeds this critical thickness, then the surface states are no longer inductively coupled. To probe the temperature-related surface to bulk transformation in conductivity of Bi
2
Se
3
, we use a high sensitivity magneto-optical imaging technique to directly image the distribution of current in single crystal and a thin film of Bi
2
Se
3
. At low temperatures, we observed a strong sheet current from the topological surface state. Above 80 K, we report that the emergence of a temperature-dependent inhomogeneous, grainy current distribution state in Bi
2
Se
3
single crystals. The grainy state has mixed regions with high and low current densities. The observation of the emergence of a temperature-dependent inhomogeneous phase in the TI suggests the possibility of a disorder-driven spontaneous phase separation scenario.
We report the generation of MeV x rays using an undulator and accelerator that are both driven by the same 100-terawatt laser system. The laser pulse driving the accelerator and the scattering laser ...pulse are independently optimized to generate a high energy electron beam (>200 MeV) and maximize the output x-ray brightness. The total x-ray photon number was measured to be ∼1×10(7), the source size was 5 μm, and the beam divergence angle was ∼10 mrad. The x-ray photon energy, peaked at 1 MeV (reaching up to 4 MeV), exceeds the thresholds of fundamental nuclear processes (e.g., pair production and photodisintegration).
PDF
