4,937 research outputs found
Flavor-twisted boundary condition for simulations of quantum many-body systems
We present an approximative simulation method for quantum many-body systems
based on coarse graining the space of the momentum transferred between
interacting particles, which leads to effective Hamiltonians of reduced size
with the flavor-twisted boundary condition. A rapid, accurate, and fast
convergent computation of the ground-state energy is demonstrated on the
spin-1/2 quantum antiferromagnet of any dimension by employing only two sites.
The method is expected to be useful for future simulations and quick estimates
on other strongly correlated systems.Comment: 6 pages, 2 figure
Optoelectronic control of spin dynamics at near-THz frequencies in magnetically doped quantum wells
We use time-resolved Kerr rotation to demonstrate the optical and electronic
tuning of both the electronic and local moment (Mn) spin dynamics in
electrically gated parabolic quantum wells derived from II-VI diluted magnetic
semiconductors. By changing either the electrical bias or the laser energy, the
electron spin precession frequency is varied from 0.1 to 0.8 THz at a magnetic
field of 3 T and at a temperature of 5 K. The corresponding range of the
electrically-tuned effective electron g-factor is an order of magnitude larger
compared with similar nonmagnetic III-V parabolic quantum wells. Additionally,
we demonstrate that such structures allow electrical modulation of local moment
dynamics in the solid state, which is manifested as changes in the amplitude
and lifetime of the Mn spin precession signal under electrical bias. The large
variation of electron and Mn-ion spin dynamics is explained by changes in
magnitude of the sp−d exchange overlap.Comment: 4 pages, 3 figure
Coercive Field and Magnetization Deficit in Ga(1-x)Mn(x)As Epilayers
We have studied the field dependence of the magnetization in epilayers of the
diluted magnetic semiconductor Ga(1-x)Mn(x)As for 0.0135 < x < 0.083.
Measurements of the low temperature magnetization in fields up to 3 T show a
significant deficit in the total moment below that expected for full saturation
of all the Mn spins. These results suggest that the spin state of the
non-ferromagnetic Mn spins is energetically well separated from the
ferromagnetism of the bulk of the spins. We have also studied the coercive
field (Hc) as a function of temperature and Mn concentration, finding that Hc
decreases with increasing Mn concentration as predicted theoretically.Comment: 15 total pages -- 5 text, 1 table, 4 figues. Accepted for publication
in MMM 2002 conference proceedings (APL
Potential field methods and their inherent approaches for path planning
Path Planning is one of the vital aspects in autonomous system. In path planning, safety is important issue that
should be taken into account in order to ensure a robot reaches at the target location without collision with surrounding
obstacles. Moreover, there are important aspects that need to be addressed in path planning; computational time, optimal
path and completeness. One of the popular methods for path planning is Potential field. Potential filed method is capable to
overcome unknown scenario, taking into account the realities of the current environment of the robot motion. Two type of
forces involved in potential field method; attractive force generated by goals and repulsive force generated by obstacles.
However, this method has a major drawback due to local minima problem. This paper reviews the traditional artificial
potential field theory that has been modified with variety of algorithms based on potential field method that have been
implemented to upgrade the potential function performance in obstacle avoidance and local minima problem
Plasmonic backscattering enhanced inverted photovoltaics
Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/98669/1/ApplPhysLett_99_113306.pd
Human genetics and genomics a decade after the release of the draft sequence of the human genome
10.1186/1479-7364-5-6-577Human Genomics56577-62
Larotrectinib efficacy and safety in TRK fusion cancer: An expanded clinical dataset showing consistency in an age and tumor agnostic approach
Background: TRK fusion cancer results from gene fusions involving NTRK1, NTRK2 or NTRK3. Larotrectinib, the first selective TRK inhibitor, has demonstrated an overall response rate (ORR) of 75% with a favorable safety profile in the first 55 consecutively enrolled adult and pediatric patients with TRK fusion cancer (Drilon et al.,NEJM2018). Here, we report the clinical activity of larotrectinib in an additional 35 TRK fusion cancer patients and provide updated follow-up of the primary analysis set (PAS) of 55 patients as of 19thFeb 2018. Methods: Patients with TRK fusion cancer detected by molecular profiling from 3 larotrectinib clinical trials (NCT02122913, NCT02637687, and NCT02576431) were eligible.Larotrectinib was administered until disease progression, withdrawal, or unacceptable toxicity. Disease status was assessed using RECIST version 1.1. Results: As of Feb 2018, by independent review, 6 PRs in the PAS deepened to CRs. The median duration of response (DoR) and progression-free survival in the PAS had still not been reached, with 12.9 months median follow-up. At 1 year, 69% of responses were ongoing, 58% of patients remained progression-free and 90% of patients were alive. An additional 19 children and 25 adults (age range, 0.1-78 years) with TRK fusion cancer were enrolled after the PAS, and included cancers of the salivary gland, thyroid, lung, colon, melanoma, sarcoma, GIST and congenital mesoblastic nephroma. In 35 evaluable patients, the ORR by investigator assessment was 74% (5 CR, 21 PR, 6 SD, 2 PD, 1 not determined). In these patients, with median follow-up of 5.5 months, median DoR had not yet been reached, and 88% of responses were ongoing at 6 months, consistent with the PAS. Adverse events (AEs) were predominantly grade 1, with dizziness, increased AST/ALT, fatigue, nausea and constipation the most common AEs reported in ≥ 10% of patients. No AE of grade 3 or 4 related to larotrectinib occurred in more than 5% of patients. Conclusions: TRK fusions are detected in a broad range of tumor types. Larotrectinib is an effective age- and tumor-agnostic treatment for TRK fusion cancer with a positive safety profile. Screening patients for NTRK gene fusions in solid- and brain tumors should be actively considered
Plasma Edge Kinetic-MHD Modeling in Tokamaks Using Kepler Workflow for Code Coupling, Data Management and Visualization
A new predictive computer simulation tool targeting the development of the H-mode pedestal at the plasma edge in tokamaks and the triggering and dynamics of edge localized modes (ELMs) is presented in this report. This tool brings together, in a coordinated and effective manner, several first-principles physics simulation codes, stability analysis packages, and data processing and visualization tools. A Kepler workflow is used in order to carry out an edge plasma simulation that loosely couples the kinetic code, XGC0, with an ideal MHD linear stability analysis code, ELITE, and an extended MHD initial value code such as M3D or NIMROD. XGC0 includes the neoclassical ion-electron-neutral dynamics needed to simulate pedestal growth near the separatrix. The Kepler workflow processes the XGC0 simulation results into simple images that can be selected and displayed via the Dashboard, a monitoring tool implemented in AJAX allowing the scientist to track computational resources, examine running and archived jobs, and view key physics data, all within a standard Web browser. The XGC0 simulation is monitored for the conditions needed to trigger an ELM crash by periodically assessing the edge plasma pressure and current density profiles using the ELITE code. If an ELM crash is triggered, the Kepler workflow launches the M3D code on a moderate-size Opteron cluster to simulate the nonlinear ELM crash and to compute the relaxation of plasma profiles after the crash. This process is monitored through periodic outputs of plasma fluid quantities that are automatically visualized with AVS/Express and may be displayed on the Dashboard. Finally, the Kepler workflow archives all data outputs and processed images using HPSS, as well as provenance information about the software and hardware used to create the simulation. The complete process of preparing, executing and monitoring a coupled-code simulation of the edge pressure pedestal buildup and the ELM cycle using the Kepler scientific workflow system is described in this paper
Capping-induced suppression of annealing in Ga(1-x)Mn(x)As epilayers
We have studied the effects of capping ferromagnetic Ga(1-x)Mn(x)As epilayers
with a thin layer of undoped GaAs, and we find that even a few monolayers of
GaAs have a significant effect on the ferromagnetic properties. In particular,
the presence of a capping layer only 10 monolayers thick completely suppresses
the enhancement of the ferromagnetism associated with low temperature
annealing. This result, which demonstrates that the surface of a Ga(1-x)Mn(x)As
epilayer strongly affects the defect structure, has important implications for
the incorporation of Ga(1-x)Mn(x)As into device heterostructures.Comment: 13 pages with figures attatche
Exchange Biasing of the Ferromagnetic Semiconductor Ga1-xMnxAs
We demonstrate the exchange coupling of a ferromagnetic semiconductor
(Ga1-xMnxAs) with an overgrown antiferromagnet (MnO). Unlike most conventional
exchange biased systems, the blocking temperature of the antiferromagnet (T_B =
48 +- 2 K) and the Curie temperature of the ferromagnet (T_C = 55.1 +- 0.2 K)
are comparable. The resulting exchange bias manifests itself as a clear shift
in the magnetization hysteresis loop when the bilayer is cooled in the presence
of an applied magnetic field and an enhancement of the coercive field.Comment: pdf file only; submitted to Applied Physics Letter
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