1,485 research outputs found
The importance of applying computational creativity to scientific and mathematical domains
Science and mathematics are currently underrepresented in the computational creativity (CC) community. We discuss why the CC community should apply their work to mathematical and scientific domains, and argue that this would be mutually beneficial for the domains in question. We identify a key challenge in Automated Reasoning – that it has not achieved widespread adoption by mathematicians; and one in Automated Scientific Discovery – the need for communicability of automatically generated scientific knowledge. We recommend that CC researchers help to address these two challenges by: (i) applying systems based on cognitive mechanisms to scientific and mathematical domains; (ii) employing experience in building and evaluating interactive systems to this context; and (iii) using expertise in automatically producing framing functionality to enhance the communicability of automatically generated scientific knowledge.EPSRC funded project EP/P017320/1 "Example-driven machine-human collaboration in mathematics
A spin qubit in a fin field-effect transistor
Quantum computing's greatest challenge is scaling up. Several decades ago,
classical computers faced the same problem and a single solution emerged:
very-large-scale integration using silicon. Today's silicon chips consist of
billions of field-effect transistors (FinFETs) in which current flow along the
fin-shaped channel is controlled by wrap-around gates. The semiconductor
industry currently employs fins of sub-10nm width, small enough for quantum
applications: at low temperature, an electron or hole can be trapped under the
gate and serve as a spin qubit. An attractive benefit of silicon's advantageous
scaling properties is that quantum hardware and its classical control circuitry
can be integrated in the same package. This, however, requires qubit operation
at temperatures greater than 1K where the cooling is sufficient to overcome
the heat dissipation. Here, we demonstrate that a silicon FinFET is an
excellent host for spin qubits that operate even above 4K. We achieve fast
electrical control of hole spins with driving frequencies up to 150MHz and
single-qubit gate fidelities at the fault-tolerance threshold. The number of
spin rotations before coherence is lost at these "hot" temperatures already
matches or exceeds values on hole spin qubits at mK temperatures. While our
devices feature both industry compatibility and quality, they are fabricated in
a flexible and agile way to accelerate their development. This work paves the
way towards large-scale integration of all-electrical and ultrafast spin
qubits
A compact and versatile cryogenic probe station for quantum device testing
Fast feedback from cryogenic electrical characterization measurements is key
for the development of scalable quantum computing technology. At room
temperature, high-throughput device testing is accomplished with a probe-based
solution, where electrical probes are repeatedly positioned onto devices for
acquiring statistical data. In this work we present a probe station that can be
operated from room temperature down to below 2K. Its small size makes it
compatible with standard cryogenic measurement setups with a magnet. A large
variety of electronic devices can be tested. Here, we demonstrate the
performance of the prober by characterizing silicon fin field-effect
transistors as a host for quantum dot spin qubits. Such a tool can massively
accelerate the design-fabrication-measurement cycle and provide important
feedback for process optimization towards building scalable quantum circuits
Further evidence for a non-cortical origin of mirror movements after stroke.
Ejaz et al. (2018) are to be commended for showing no
evidence for a cortical origin of post-stroke mirror movements.
Using functional MRI during affected-finger presses
in recovering adult-onset stroke patients, they found no
consistent relationship between contralesional sensorimotor
cortex (cSM1) activation and quantitative indices of mirror
movements; specifically, mirror movements were not linked
to the presence of cSM1 overactivation, arguing against the
classic ‘transcallosal’ mechanism heretofore widely believed
to cause mirror movements (Di Pino et al., 2014). We wish
to report findings—previously published in abstract form
(Calautti, 2008)—that further support the idea that
mirror movements are not cortically mediated. We also
present data that confirm that mirror movements can
involve the affected (i.e. paretic) hand during movement
of the unaffected (i.e. non-paretic) hand, also arguing in
favour of disruption of a bilaterally-organized system
Silicon quantum dot devices with a self-aligned second gate layer
We implement silicon quantum dot devices with two layers of gate electrodes
using a self-alignment technique, which allows for ultra-small gate lengths and
intrinsically perfect layer-to-layer alignment. In a double quantum dot system,
we investigate hole transport and observe current rectification due to Pauli
spin blockade. Magnetic field measurements indicate that hole spin relaxation
is dominated by spin-orbit interaction, and enable us to determine the
effective hole -factor . From an avoided singlet-triplet
crossing, occurring at high magnetic field, the spin-orbit coupling strength
meV is obtained, promising fast and all-electrical spin control
Study protocol for a randomised controlled trial of invasive versus conservative management of primary spontaneous pneumothorax
INTRODUCTION: Current management of primary spontaneous pneumothorax (PSP) is variable, with little evidence from randomised controlled trials to guide treatment. Guidelines emphasise intervention in many patients, which involves chest drain insertion, hospital admission and occasionally surgery. However, there is evidence that conservative management may be effective and safe, and it may also reduce the risk of recurrence. Significant questions remain regarding the optimal initial approach to the management of PSP
Effects of deformation in the three-body structure of 11Li
11Li is studied within a three-body model 9Li+n+n where the core is allowed
to be deformed and/or excite. In particular, we include reorientation couplings
and couplings between the two bound states of 9Li. Contrary to the other
examples studied within this model, we find that core excitation does not
affect the structure of 11Li significantly. Reorientation couplings of the
deformed 9Li can change the ground state of 11Li from a predominantly two
neutron s1/2^2 configuration into a p1/2^2. In addition, we see no evidence for
the existence of significant d-wave strength in its ground state, as opposed to
the prediction by shell model. A comparison with shell model is presented.Comment: 13 pages, 9 figure
Artificial Intelligence and the Future of Work: A Functional-Identity Perspective
The impact of the implementation of artificial intelligence (AI) on workers’ experiences remains underexamined. Although AI-enhanced processes can benefit workers (e.g., by assisting with exhausting or dangerous tasks), they can also elicit psychological harm (e.g., by causing job loss or degrading work quality). Given AI’s uniqueness among other technologies, resulting from its expanding capabilities and capacity for autonomous learning, we propose a functional-identity framework to examine AI’s effects on people’s work-related self-understandings and the social environment at work. We argue that the conditions for AI to either enhance or threaten workers’ sense of identity derived from their work depends on how the technology is functionally deployed (by complementing tasks, replacing tasks, and/or generating new tasks) and how it affects the social fabric of work. Also, how AI is implemented and the broader social-validation context play a role. We conclude by outlining future research directions and potential application of the proposed framework to organizational practice
Relationships between selective neuronal loss and microglial activation after ischaemic stroke in man.
Modern ischaemic stroke management involves intravenous thrombolysis followed by mechanical thrombectomy, which allows markedly higher rates of recanalization and penumbral salvage than thrombolysis alone. However, <50% of treated patients eventually enjoy independent life. It is therefore important to identify complementary therapeutic targets. In rodent models, the salvaged penumbra is consistently affected by selective neuronal loss, which may hinder recovery by interfering with plastic processes, as well as by microglial activation, which may exacerbate neuronal death. However, whether the salvaged penumbra in man is similarly affected is still unclear. Here we determined whether these two processes affect the non-infarcted penumbra in man and, if so, whether they are inter-related. We prospectively recruited patients with (i) acute middle-cerebral artery stroke; (ii) penumbra present on CT perfusion obtained <4.5 h of stroke onset; and (iii) early neurological recovery as a marker of penumbral salvage. PET with 11C-flumazenil and 11C-PK11195, as well as MRI to map the final infarct, were obtained at predefined follow-up times. The presence of selective neuronal loss and microglial activation was determined voxel-wise within the MRI normal-appearing ipsilateral non-infarcted zone and surviving penumbra masks, and their inter-relationship was assessed both across and within patients. Dilated infarct contours were consistently excluded to control for partial volume effects. Across the 16 recruited patients, there was reduced 11C-flumazenil and increased 11C-PK11195 binding in the whole ipsilateral non-infarcted zone (P = 0.04 and 0.02, respectively). Within the non-infarcted penumbra, 11C-flumazenil was also reduced (P = 0.001), but without clear increase in 11C-PK11195 (P = 0.18). There was no significant correlation between 11C-flumazenil and 11C-PK11195 in either compartment. This mechanistic study provides direct evidence for the presence of both neuronal loss and microglial activation in the ipsilateral non-infarcted zone. Further, we demonstrate the presence of neuronal loss affecting the surviving penumbra, with no or only mild microglial activation, and no significant relationship between these two processes. Thus, microglial activation may not contribute to penumbral neuronal loss in man, and its presence in the ipsilateral hemisphere may merely reflect secondary remote degeneration. Selective neuronal loss in the surviving penumbra may represent a novel therapeutic target as an adjunct to penumbral salvage to further improve functional outcome. However, microglial activation may not stand as the primary therapeutic approach. Protecting the penumbra by acutely improving perfusion and oxygenation in conjunction with thrombectomy for example, may be a better approach. 11C-flumazenil PET would be useful to monitor the effects of such therapies
Structure of unstable light nuclei
The structure of light nuclei out to the drip lines and beyond up to Z = 8 is
interpreted in terms of the shell model. Special emphasis is given to the
underlying supermultiplet symmetry of the p-shell nuclei which form cores for
neutrons and protons added in sd-shell orbits. Detailed results are given on
the wave functions, widths, and Coulomb energy shifts for a wide range of
non-normal parity states in the p-shell.Comment: 21 pages, to appear in Nuclear Physics
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