644 research outputs found
Adult neurogenesis and specific replacement of interneuron subtypes in the mouse main olfactory bulb
Expression and signal transduction of the glucagon receptor in βTC3 cells
AbstractThe expression and signal transduction of the glucagon receptor (GR) have been studied in βTC3 cells. Northern blot and RT-PCR analysis indicated the expression of the GR gene in βTC3 cells. One-5 nM glucagon stimulated a 2.5-fold increase in the IPs production. At glucagon concentrations higher than 5 nM, the production of IPs was blunted but not abolished. The accumulation of intracellular cAMP was observed following the stimulation with 5 nM of glucagon. A maximal 4.5-fold increase in cAMP was observed using 250 nM glucagon and higher. Comparative studies using a glucagon anatogonist, des-His1[Glu]9glucagon, showed no effect on intracellular cAMP and IPs in βTC3 cells. Our data shows that the GR gene is expressed in βTC3 cells. The GR in βTC3 cells transmits its intracellular signal by causing the accumulation of both IPs and cAMP
Showcasing a Barren Plateau Theory Beyond the Dynamical Lie Algebra
Barren plateaus have emerged as a pivotal challenge for variational quantum
computing. Our understanding of this phenomenon underwent a transformative
shift with the recent introduction of a Lie algebraic theory capable of
explaining most sources of barren plateaus. However, this theory requires
either initial states or observables that lie in the circuit's Lie algebra.
Focusing on parametrized matchgate circuits, in this work we are able to go
beyond this assumption and provide an exact formula for the loss function
variance that is valid for arbitrary input states and measurements. Our results
reveal that new phenomena emerge when the Lie algebra constraint is relaxed.
For instance, we find that the variance does not necessarily vanish inversely
with the Lie algebra's dimension. Instead, this measure of expressiveness is
replaced by a generalized expressiveness quantity: The dimension of the Lie
group modules. By characterizing the operators in these modules as products of
Majorana operators, we can introduce a precise notion of generalized globality
and show that measuring generalized-global operators leads to barren plateaus.
Our work also provides operational meaning to the generalized entanglement as
we connect it with known fermionic entanglement measures, and show that it
satisfies a monogamy relation. Finally, while parameterized matchgate circuits
are not efficiently simulable in general, our results suggest that the
structure allowing for trainability may also lead to classical simulability.Comment: 5+26 pages, 2+1 figure
Current and Emerging Pharmacotherapies for Primary CNS Lymphoma
Primary central nervous system lymphoma (PCNSL) constitutes a rare group of extranodal non-Hodgkin’s lymphoma (NHL) primarily of B cell origin. It occurs in both immuno-competent and immune-compromised patients. High dose m ethotrexate (HD-MTX) based chemotherapy is the standard therapy. Chemotherapy with whole brain radiation therapy (WBRT) improves response rates and survival compared with WBRT alone. However, due to the increased risk for neurotoxicity with WBRT, recent studies have focused on using chemotherapy alone. Methotrexate based multi-agent chemotherapy without WBRT is associated with similar t reatment rates and survival compared with regimens that include WBRT although controlled trials have not been performed. Because of the low incidence of this disease, it is difficult to conduct randomized controlled trials. In this article we have discussed about the past, present and emerging treatment options in patients with PCNSL
Applications of Optical Fiber Assemblies in Harsh Environments, the Journey Past, Present and Future
Over the past ten years, NASA has studied the effects of harsh environments on optical fiber assemblies for communication systems, lidar systems, and science missions. The culmination of this has resulted in recent technologies that are unique and tailored to meeting difficult requirements under challenging performance constraints. This presentation will focus on the past mission applications of optical fiber assemblies including; qualification information, lessons learned and new technological advances that will enable the road ahead
Development, Qualification and Integration of the Optical Fiber Array Assemblies for the Lunar Reconnaissance Orbiter
The NASA Goddard Fiber Optics Team in the Electrical Engineering Division of the Applied Engineering and Technology Directorate, designed, developed and integrated the space flight optical fiber array hardware for the Lunar Reconnaissance Orbiter (LRO). The two new assemblies that were designed and manufacturing at GSFC for the LRO exist in configurations that are unique in the world for the application of ranging and LIDAR. Described here is an account of the journey and the lessons learned from design to integration for the Lunar Orbiter Laser Altimeter and the Laser Ranging Application on the LRO
Parallel-in-time quantum simulation via Page and Wootters quantum time
In the past few decades, researchers have created a veritable zoo of quantum
algorithm by drawing inspiration from classical computing, information theory,
and even from physical phenomena. Here we present quantum algorithms for
parallel-in-time simulations that are inspired by the Page and Wooters
formalism. In this framework, and thus in our algorithms, the classical
time-variable of quantum mechanics is promoted to the quantum realm by
introducing a Hilbert space of "clock" qubits which are then entangled with the
"system" qubits. We show that our algorithms can compute temporal properties
over different times of many-body systems by only using clock
qubits. As such, we achieve an exponential trade-off between time and spatial
complexities. In addition, we rigorously prove that the entanglement created
between the system qubits and the clock qubits has operational meaning, as it
encodes valuable information about the system's dynamics. We also provide a
circuit depth estimation of all the protocols, showing an exponential advantage
in computation times over traditional sequential in time algorithms. In
particular, for the case when the dynamics are determined by the Aubry-Andre
model, we present a hybrid method for which our algorithms have a depth that
only scales as . As a by product we can relate the
previous schemes to the problem of equilibration of an isolated quantum system,
thus indicating that our framework enable a new dimension for studying
dynamical properties of many-body systems.Comment: 19+15 pages, 18+1 figure
Fiber Optic Cable Thermal Preparation to Ensure Stable Operation
Fiber optic cables are widely used in modern systems that must provide stable operation during exposure to changing environmental conditions. For example, a fiber optic cable on a satellite may have to reliably function over a temperature range of -50 C up to 125 C. While the system requirements for a particular application will dictate the exact method by which the fibers should be prepared, this work will examine multiple ruggedized fibers prepared in different fashions and subjected to thermal qualification testing. The data show that if properly conditioned the fiber cables can provide stable operation, but if done incorrectly, they will have large fluctuations in transmission
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