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"Research—Laboratory"
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Electronic read-out of a single nuclear spin using a molecular spin transistor
The long-lived nuclear spin state of an individual metal atom embedded in a single-molecule magnet is shown to be readable electronically.
Nuclear spins for quantum computing
Nuclear spins are increasingly being considered for the role of active elements in a quantum computer: in contrast to electronic spins they are well isolated from the environment, a favourable condition for achieving stable quantum coherence. The challenge is to address and manipulate these spins. Romain Vincent
et al
. bring such applications closer by showing that the long-lived nuclear-spin state of an individual metal atom embedded in a single-molecule magnet can be read electronically. They observe long nuclear-spin lifetimes — tens of seconds — and are able to determine the dynamics of spin states.
Quantum control of individual spins in condensed-matter devices is an emerging field with a wide range of applications, from nanospintronics
1
,
2
to quantum computing
3
. The electron, possessing spin and orbital degrees of freedom, is conventionally used as the carrier of quantum information in proposed devices
4
,
5
,
6
,
7
,
8
,
9
. However, electrons couple strongly to the environment, and so have very short relaxation and coherence times. It is therefore extremely difficult to achieve quantum coherence and stable entanglement of electron spins. Alternative concepts propose nuclear spins as the building blocks for quantum computing
10
, because such spins are extremely well isolated from the environment and less prone to decoherence. However, weak coupling comes at a price: it remains challenging to address and manipulate individual nuclear spins
11
,
12
,
13
,
14
. Here we show that the nuclear spin of an individual metal atom embedded in a single-molecule magnet can be read out electronically. The observed long lifetimes (tens of seconds) and relaxation characteristics of nuclear spin at the single-atom scale open the way to a completely new world of devices in which quantum logic may be implemented.
Journal Article
Optically mediated particle clearing using Airy wavepackets
The Airy wavepacket solution for a free particle exhibits propagation invariance and, surprisingly, acceleration transverse to the propagation direction
1
. Discovered as a solution of the free-particle Schrödinger equation, Airy wavepackets have been predicted
2
, and in a recent major step forward, realized
3
in the optical domain, but have never been used in any application. In this Letter we demonstrate the first use of the Airy light beam in optical micromanipulation
4
,
5
. Based on the characteristic intensity pattern, the beam drags particles into the main intensity maximum, which guides particles vertically along a parabolic trajectory. This unusual property of Airy beams leads to a new feature in optical micromanipulation—the removal of particles and cells from a section of a sample chamber. We term this highly robust and efficient process ‘optically mediated particle clearing’, which enables novel microfluidic applications within the colloidal and biological sciences.
Scientists exploit the use of Airy beams — an unusual class of optical waves — in optical manipulation. The beam can be used to transport particles along curved paths without moving the light beam, a technique that seems poised for many microfluidic applications especially in the biological sciences.
Journal Article
Machine Learning Using Multiparametric Magnetic Resonance Imaging Radiomic Feature Analysis to Predict Ki-67 in World Health Organization Grade I Meningiomas
Abstract
BACKGROUND
Although World Health Organization (WHO) grade I meningiomas are considered “benign” tumors, an elevated Ki-67 is one crucial factor that has been shown to influence tumor behavior and clinical outcomes. The ability to preoperatively discern Ki-67 would confer the ability to guide surgical strategy.
OBJECTIVE
In this study, we develop a machine learning (ML) algorithm using radiomic feature analysis to predict Ki-67 in WHO grade I meningiomas.
METHODS
A retrospective analysis was performed for a cohort of 306 patients who underwent surgical resection of WHO grade I meningiomas. Preoperative magnetic resonance imaging was used to perform radiomic feature extraction followed by ML modeling using least absolute shrinkage and selection operator wrapped with support vector machine through nested cross-validation on a discovery cohort (n = 230), to stratify tumors based on Ki-67 <5% and ≥5%. The final model was independently tested on a replication cohort (n = 76).
RESULTS
An area under the receiver operating curve (AUC) of 0.84 (95% CI: 0.78-0.90) with a sensitivity of 84.1% and specificity of 73.3% was achieved in the discovery cohort. When this model was applied to the replication cohort, a similar high performance was achieved, with an AUC of 0.83 (95% CI: 0.73-0.94), sensitivity and specificity of 82.6% and 85.5%, respectively. The model demonstrated similar efficacy when applied to skull base and nonskull base tumors.
CONCLUSION
Our proposed radiomic feature analysis can be used to stratify WHO grade I meningiomas based on Ki-67 with excellent accuracy and can be applied to skull base and nonskull base tumors with similar performance achieved.
Journal Article
The American Lab : An insider's history of the Lawrence Livermore National Laboratory
\"In The American Lab, former LLNL director Bruce Tarter captures the spirit of the Laboratory and its reflection of the broader world in which it thrived. He identifies the major themes that have characterized science and technology in the latter half of the twentieth century--the growth and decline of nuclear warheads, the unprecedented rise of supercomputing technology, laser systems, fusion, and mass spectrometry. He illuminates the Cold War dynamic from the participants' point of view--an unusual and valuable perspective on nuclear history. The story of the laboratory is a tale of three eras. Although the Lab took its research vision from European Edward Teller, its modus operandi came almost exclusively from namesake Ernest Lawrence and was subsequently invented in-house by its scientists and staff. During its first two decades the Lab's focus was almost entirely on nuclear weapons research and development, with a few other smaller enterprises that were technically related to the nuclear weapons activities. In the 1970s and 1980s, the Laboratory, along with many others in the Department of Energy complex, expanded into civilian pursuits that included energy, environment, biology, and basic science. A major program in laser science and technology became a cornerstone of this period. The third era was initiated by the end of the Cold War and saw the transformation of the traditional nuclear weapons activities into the stockpile stewardship program along with the rapid growth of projects that can be broadly characterized as homeland security. Tarter's history/memoir of the Lawrence Livermore National Laboratory, provides an insider's examination of nuclear science in the Cold War and the technological shift that occurred after the fall of the Berlin Wall.\"--Provided by publisher.
Book
Developing optofluidic technology through the fusion of microfluidics and optics
We describe devices in which optics and fluidics are used synergistically to synthesize novel functionalities. Fluidic replacement or modification leads to reconfigurable optical systems, whereas the implementation of optics through the microfluidic toolkit gives highly compact and integrated devices. We categorize optofluidics according to three broad categories of interactions: fluid–solid interfaces, purely fluidic interfaces and colloidal suspensions. We describe examples of optofluidic devices in each category.
Journal Article
Animal ethos : the morality of human-animal encounters in experimental lab science
\"What are the moral challenges and consequences of animal research in academic laboratory settings? Animal Ethos considers how the inescapable needs of lab research necessitate interspecies encounters that, in turn, engender unexpected moral responses among a range of associated personnel. Whereas much has been written about codified, bioethical rules and regulations that inform proper lab behavior and decorum, Animal Ethos, as an in-depth, ethnographic project, probes the equally rich--yet poorly understood--realm of ordinary or everyday morality, where serendipitous, creative, and unorthodox thought and action evidence concerted efforts to transform animal laboratories into moral, scientific worlds. The work is grounded in efforts to integrate theory within medical anthropology (and, more particularly, on suffering and moral worth), animal studies, and science and technology studies (STS). Contrary to established scholarship that focuses exclusively on single professions (such as the researcher or technician), Animal Ethos tracks across the spectrum of the lab labor hierarchy by considering the experiences of researchers, animal technicians, and lab veterinarians. In turn, it offers comparative insights on animal activists. When taken together, this range of parties illuminates the moral complexities of experimental lab research. The affective qualities of interspecies intimacy, animal death, and species preference are of special analytical concern, as reflected in the themes of 'Intimacy,' 'Sacrifice,' and 'Exceptionalism' that anchor this work\"--Provided by publisher.
Book
The origins and the future of microfluidics
The manipulation of fluids in channels with dimensions of tens of micrometres — microfluidics — has emerged as a distinct new field. Microfluidics has the potential to influence subject areas from chemical synthesis and biological analysis to optics and information technology. But the field is still at an early stage of development. Even as the basic science and technological demonstrations develop, other problems must be addressed: choosing and focusing on initial applications, and developing strategies to complete the cycle of development, including commercialization. The solutions to these problems will require imagination and ingenuity.
Journal Article