13,434 research outputs found
Choosing the lesser of two evils, the better of two goods: Specifying the roles of ventromedial prefrontal cortex and dorsal anterior cingulate in object choice
The ventromedial prefrontal cortex (vmPFC) and dorsal anterior cingulate cortices (ACd) are considered important for reward-based decision making. However, work distinguishing their individual functional contributions has only begun. One aspect of decision making that has received little attention is that making the right choice often translates to making the better choice. Thus, response choice often occurs in situations where both options are desirable (e.g., choosing between mousse au chocolat or crème caramel cheesecake from a menu) or, alternatively, in situations where both options are undesirable. Moreover, response choice is easier when the reinforcements associated with the objects are far apart, rather than close together, in value. We used functional magnetic resonance imaging to delineate the functional roles of the vmPFC and ACd by investigating these two aspects of decision making: (1) decision form (i.e., choosing between two objects to gain the greater reward or the lesser punishment), and (2) between-object reinforcement distance (i.e., the difference in reinforcements associated with the two objects). Blood oxygen level-dependent (BOLD) responses within the ACd and vmPFC were both related to decision form but differentially. Whereas ACd showed greater responses when deciding between objects to gain the lesser punishment, vmPFC showed greater responses when deciding between objects to gain the greater reward. Moreover, vmPFC was sensitive to reinforcement expectations associated with both the chosen and the forgone choice. In contrast, BOLD responses within ACd, but not vmPFC, related to between-object reinforcement distance, increasing as the distance between the reinforcements of the two objects decreased. These data are interpreted with reference to models of ACd and vmPFC functioning
Abelian link invariants and homology
We consider the link invariants defined by the quantum Chern-Simons field
theory with compact gauge group U(1) in a closed oriented 3-manifold M. The
relation of the abelian link invariants with the homology group of the
complement of the links is discussed. We prove that, when M is a homology
sphere or when a link -in a generic manifold M- is homologically trivial, the
associated observables coincide with the observables of the sphere S^3. Finally
we show that the U(1) Reshetikhin-Turaev surgery invariant of the manifold M is
not a function of the homology group only, nor a function of the homotopy type
of M alone.Comment: 18 pages, 3 figures; to be published in Journal of Mathematical
Physic
Measuring the success of reducing emissions using an on-board eco-driving feedback tool
This paper reports the findings of an eco-driving trial that was designed enable users to make pre-trip and on-route decisions when driving as to the optimal route to take. The basis of this paper will be to estimate how efficiently drivers are performing in relation to fuel consumption per kilometres (km). The analysis uses details on the vehicle specification, in terms of fuel efficiency, and relates this to the distance travelled to provide the user with information on the efficiency per km travelled. Eco-driving involves the training of individuals to change their driving patterns and to adapt to driving conditions. The results of the study show that eco-driving feedback is a powerful tool and how it can be used to reduce emissions
Probing anharmonic properties of nuclear surface vibration by heavy-ion fusion reactions
Describing fusion reactions between ^{16}O and ^{154}Dy and, between ^{16}O
and ^{144}Sm by the and interacting boson model, we show that
heavy-ion fusion reactions are strongly affected by anharmonic properties of
nuclear surface vibrations and nuclear shape, and thus provide a powerful
method to study details of nuclear structure and dynamics.Comment: 8 pages, 5 figures, To be published in the Proceedings of the FUSION
97 Conference, South Durras, Australia, March 1997 (J. Phys. G
Reading Disorders
There are two major types of reading disorder; developmental dyslexia and reading comprehension impairment. The primary difficulty in dyslexia is with the accurate and fluent reading of single words, whilst in reading comprehension impairment words can be read accurately but there is no or
little understanding of what is read. Using the causal modelling framework, the underlying causes of the two disorders are reviewed together with the co-occurrence of reading and language disorders. The rationale for viewing reading as a dimensional disorder, where the difficulties experienced are on a continuum rather than using cut-off points to identify disorders is also reviewed
Evidence of Double Phonon Excitations in ^{16}O + ^{208}Pb Reaction
The fusion cross-sections for ^{16}O + ^{208}Pb, measured to high precision,
enable the extraction of the distribution of fusion barriers. This shows a
structure markedly different from the single-barrier which might be expected
for fusion of two doubly-closed shell nuclei. The results of exact coupled
channel calculations performed to understand the observations are presented.
These calculations indicate that coupling to a double octupole phonon excited
state in ^{208}Pb is necessary to explain the experimental barrier
distributions.Comment: 6 pages, 2 figures, To be published in the Proceedings of the FUSION
97 Conference, South Durras, Australia, March 1997 (J. Phys. G
Bound states of edge dislocations: The quantum dipole problem in two dimensions
We investigate bound state solutions of the 2D Schr\"odinger equation with a
dipole potential originating from the elastic effects of a single edge
dislocation. The knowledge of these states could be useful for understanding a
wide variety of physical systems, including superfluid behavior along
dislocations in solid He. We present a review of the results obtained by
previous workers together with an improved variational estimate of the ground
state energy. We then numerically solve the eigenvalue problem and calculate
the energy spectrum. In our dimensionless units, we find a ground state energy
of -0.139, which is lower than any previous estimate. We also make successful
contact with the behavior of the energy spectrum as derived from semiclassical
considerations.Comment: 6 pages, 3 figures, submitted to PR
Effect of oil palm sustainability certification on deforestation and fire in Indonesia.
Many major corporations and countries have made commitments to purchase or produce only "sustainable" palm oil, a commodity responsible for substantial tropical forest loss. Sustainability certification is the tool most used to fulfill these procurement policies, and around 20% of global palm oil production was certified by the Roundtable on Sustainable Palm Oil (RSPO) in 2017. However, the effect of certification on deforestation in oil palm plantations remains unclear. Here, we use a comprehensive dataset of RSPO-certified and noncertified oil palm plantations (∼188,000 km2) in Indonesia, the leading producer of palm oil, as well as annual remotely sensed metrics of tree cover loss and fire occurrence, to evaluate the impact of certification on deforestation and fire from 2001 to 2015. While forest loss and fire continued after RSPO certification, certified palm oil was associated with reduced deforestation. Certification lowered deforestation by 33% from a counterfactual of 9.8 to 6.6% y-1 Nevertheless, most plantations contained little residual forest when they received certification. As a result, by 2015, certified areas held less than 1% of forests remaining within Indonesian oil palm plantations. Moreover, certification had no causal impact on forest loss in peatlands or active fire detection rates. Broader adoption of certification in forested regions, strict requirements to avoid all peat, and routine monitoring of clearly defined forest cover loss in certified and RSPO member-held plantations appear necessary if the RSPO is to yield conservation and climate benefits from reductions in tropical deforestation
Electrical activation and electron spin resonance measurements of implanted bismuth in isotopically enriched silicon-28
We have performed continuous wave and pulsed electron spin resonance
measurements of implanted bismuth donors in isotopically enriched silicon-28.
Donors are electrically activated via thermal annealing with minimal diffusion.
Damage from bismuth ion implantation is repaired during thermal annealing as
evidenced by narrow spin resonance linewidths (B_pp=12uT and long spin
coherence times T_2=0.7ms, at temperature T=8K). The results qualify ion
implanted bismuth as a promising candidate for spin qubit integration in
silicon.Comment: 4 pages, 4 figure
Ultraviolet Imaging Observations of the cD Galaxy in Abell 1795: Further Evidence for Massive Star Formation in a Cooling Flow
We present images from the Ultraviolet Imaging Telescope of the Abell 1795
cluster of galaxies. We compare the cD galaxy morphology and photometry of
these data with those from existing archival and published data. The addition
of a far--UV color helps us to construct and test star formation model
scenarios for the sources of UV emission. Models of star formation with rates
in the range \sim5-20M_{\sun}yr indicate that the best fitting models
are those with continuous star formation or a recent ( Myr old) burst
superimposed on an old population. The presence of dust in the galaxy,
dramatically revealed by HST images complicates the interpretation of UV data.
However, we find that the broad--band UV/optical colors of this cD galaxy can
be reasonably matched by models using a Galactic form for the extinction law
with . We also briefly discuss other objects in the large UIT
field of view.Comment: To appear in the Astrophysical Journal. 14 AAS preprint style pages
plus 7 figure
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