Electronic Structure of Multiple Dots

We calculate, via spin density functional theory (SDFT) and exact diagonalization, the eigenstates for electrons in a variety of external potentials, including double and triple dots. The SDFT calculations employ realistic wafer profiles and gate geometries and also serve as the basis for the exact diagonalization calculations. The exchange interaction J between electrons is the difference between singlet and triplet ground state energies and reflects competition between tunneling and the exchange matrix element, both of which result from overlap in the barrier. For double dots, a characteristic transition from singlet ground state to triplet ground state (positive to negative J) is calculated. For the triple dot geometry with 2 electrons we also find the electronic structure with exact diagonalization. For larger electron number (18 and 20) we use only SDFT. In contrast to the double dot case, the triple dot case shows a quasi-periodic fluctuation of J with magnetic field which we attribute to periodic variations of the basis states in response to changing flux quanta threading the triple dot structure.Comment: 3 pages, 4 figure

The Kinetics of the Formation of Aluminium Hydroxide by Seeding Sodium Aluminate Solutions with Hydrargillite Crystals. III. The Effect of Coarse-Grained Seed

We conclruded from the fig. 2/ c in our second report, that nucleation was caused only by fine particles and independetly from the coarser ones which played quite a passive role. We are presenting direct evidence for this statement

The Kinetics of the Formation of Aluminium Hydroxideby Seeding Sodium Aluminate Solutions with Hydrargillite Crystals IV. On the »Contact-intercrystallization«

It is shown that agglomeration of fine particles takes place in this system by the contact of crystallites. This mechanism is very quick and does not involve any measurable separation of a new solid phase from the solution. The name »contact-intercrystallization« is proposed. The most suitable way of evaluating the weight- size-distribution results is discussed. A method for distinguishing between various crystallization- mechanisms is proposed and some suggestions for practical application are given

Presumed Pediatric Isolated Oculomotor Nerve Schwannoma - A Case Report

Shadi Boqaaiya,1 Aman Raed,1,2 Aviv Vidan,1,2 Karine Beiruti Wiegler,3 Yuval Cohen,1,2 Otzem Chassid1,2 1Ziv Medical Center; Department of Ophthalmology, Safed, 1311001, Israel; 2Azrieli Faculty of Medicine, Bar-Ilan University, Safed, 1311502, Israel; 3Research Wing, Ziv Medical Centre, Safed, 1311001, IsraelCorrespondence: Otzem Chassid, Department of Ophthalmology, Ziv Medical Center, Harambam Street 1, Safed, 1311001, Israel, Tel +972 506266059, Email [email protected]: This report presents a healthy 2.5-year-old child exhibiting headache, ptosis, exotropia, and left mydriasis. Initial neuroimaging, including computed tomography (CT), computed tomography angiography (CTA), and standardized magnetic resonance imaging (MRI), failed to identify any lesions; however, high-resolution MRI revealed an ovoid mass adjacent to the left proximal oculomotor nerve within the superior cavernous sinus. This case underscores the necessity for advanced imaging techniques and a thorough diagnostic approach to enhance understanding of this rare pediatric condition. Moreover, it highlights the limited documentation of pediatric oculomotor schwannomas, leading to an inadequate understanding of their diagnosis and management, and emphasizes the need for enhanced awareness and research to establish effective diagnostic protocols, particularly utilizing advanced neuroimaging techniques.Keywords: headache, peri-tumoral edema, third nerve palsy, high-resolution MRI, steroid

A joint physics and radiobiology DREAM team vision - Towards better response prediction models to advance radiotherapy.

Radiotherapy developed empirically through experience balancing tumour control and normal tissue toxicities. Early simple mathematical models formalized this practical knowledge and enabled effective cancer treatment to date. Remarkable advances in technology, computing, and experimental biology now create opportunities to incorporate this knowledge into enhanced computational models. The ESTRO DREAM (Dose Response, Experiment, Analysis, Modelling) workshop brought together experts across disciplines to pursue the vision of personalized radiotherapy for optimal outcomes through advanced modelling. The ultimate vision is leveraging quantitative models dynamically during therapy to ultimately achieve truly adaptive and biologically guided radiotherapy at the population as well as individual patient-based levels. This requires the generation of models that inform response-based adaptations, individually optimized delivery and enable biological monitoring to provide decision support to clinicians. The goal is expanding to models that can drive the realization of personalized therapy for optimal outcomes. This position paper provides their propositions that describe how innovations in biology, physics, mathematics, and data science including AI could inform models and improve predictions. It consolidates the DREAM team's consensus on scientific priorities and organizational requirements. Scientifically, it stresses the need for rigorous, multifaceted model development, comprehensive validation and clinical applicability and significance. Organizationally, it reinforces the prerequisites of interdisciplinary research and collaboration between physicians, medical physicists, radiobiologists, and computational scientists throughout model development. Solely by a shared understanding of clinical needs, biological mechanisms, and computational methods, more informed models can be created. Future research environment and support must facilitate this integrative method of operation across multiple disciplines

Few-electron quantum dots for quantum computing

Two tunnel-coupled few-electron quantum dots were fabricated in a GaAs/AlGaAs quantum well. The absolute number of electrons in each dot could be determined from finite bias Coulomb blockade measurements and gate voltage scans of the dots, and allows the number of electrons to be controlled down to zero. The Zeeman energy of several electronic states in one of the dots was measured with an in-plane magnetic field, and the g-factor of the states was found to be no different than that of electrons in bulk GaAs. Tunnel-coupling between dots is demonstrated, and the tunneling strength was estimated from the peak splitting of the Coulomb blockade peaks of the double dot.Comment: 11 pages, 5 figures. Website at http://meso.deas.harvard.ed

Ge/Si nanowire mesoscopic Josephson junctions

The controlled growth of nanowires (NWs) with dimensions comparable to the Fermi wavelengths of the charge carriers allows fundamental investigations of quantum confinement phenomena. Here, we present studies of proximity-induced superconductivity in undoped Ge/Si core/shell NW heterostructures contacted by superconducting leads. By using a top gate electrode to modulate the carrier density in the NW, the critical supercurrent can be tuned from zero to greater than 100 nA. Furthermore, discrete sub-bands form in the NW due to confinement in the radial direction, which results in stepwise increases in the critical current as a function of gate voltage. Transport measurements on these superconductor-NW-superconductor devices reveal high-order (n = 25) resonant multiple Andreev reflections, indicating that the NW channel is smooth and the charge transport is highly coherent. The ability to create and control coherent superconducting ordered states in semiconductor-superconductor hybrid nanostructures allows for new opportunities in the study of fundamental low-dimensional superconductivity