1,197 research outputs found
Does Company Specific News Effect the US, UK, and Australian Markets within 60 minutes?
The efficient market hypothesis states that an efficient market rapidly incorporates all available information into the price of the asset. It has been well established that no market, particularly the stock market, is truly efficient as there are too many traders with differing strategies, and differing access to and interpretation of information. Despite this there is considerable evidence that the stock market does assimilate new information into prices. There has however been little research into the intraday effect of company specific news. In this paper we investigate the intraday effect of company specific news on the US, UK, and Australian markets. We use a scheme to determine whether the markets react to news by determining the likelihood of certain events occurring, and the likelihood of news occurring within 60 minutes of them, and compare the two. We find that there is strong evidence that these markets do react to news within 60 minutes, and indicate which events are most likely to correlate to news.Return; Volatility; News
A Discrete Four Stroke Quantum Heat Engine Exploring the Origin of Friction
The optimal power performance of a first principle quantum heat engine model
shows friction-like phenomena when the internal fluid Hamiltonian does not
commute with the external control field. The model is based on interacting
two-level-systems where the external magnetic field serves as a control
variable.Comment: 4 pages 3 figure
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A Distributed Conncetionist Representation for Concept Structures
We describe a representation for frame-like concept structures ina neural network called DUCS. Slot names and slot fillers axe diffuse patternsof activation spread over a collection of units. Our choice of a distributedrepresentation gives rise to certain useful properties not shaied by conventionalframe systems. One of these is the ability to encode fine semantic distinctions assubtle vairiations on the canonical pattern for a slot. D U C S typically maintainsseveral concepts simultaneously in its concept memory; it can retrieve a conceptgiven one or more slots as cues. W e show how Hinton's notion of a "reduceddescription" cam be used to make one concept fill a slot in another
Dominant hemisphere functional networks compensate for structural connectivity loss to preserve phonological retrieval with aging
Introduction
Loss of hemispheric asymmetry during cognitive tasks has been previously demonstrated in the literature. In the context of language, increased right hemisphere activation is observed with aging. Whether this relates to compensation to preserve cognitive function or dedifferentiation implying loss of hemispheric specificity without functional consequence, remains unclear.
Methods
With a multifaceted approach, integrating structural and functional imaging data during a word retrieval task, in a group of younger and older adults with equivalent cognitive performance, we aimed to establish whether interactions between hemispheres or reorganization of dominant hemisphere networks preserve function. We examined functional and structural connectivity on data from our previously published functional activation study. Functional connectivity was measured using psychophysiological interactions analysis from the left inferior frontal gyrus (LIFG) and the left insula (LINS), based on published literature, and the right inferior frontal gyrus (RIFG) based on our previous study.
Results
Although RIFG showed increased activation, its connectivity decreased with age. Meanwhile, LIFG and LINS connected more bilaterally in the older adults. White matter integrity, measured by fractional anisotropy (FA) from diffusion tensor imaging, decreased significantly in the older group. Importantly, LINS functional connectivity to LIFG correlated inversely with FA.
Conclusions
We demonstrate that left hemispheric language areas show higher functional connectivity in older adults with intact behavioral performance, and thus, may have a role in preserving function. The inverse correlation of functional and structural connectivity with age is in keeping with emerging literature and merits further investigation with tractography studies and in other cognitive domains
A quantum-mechanical Maxwell's demon
A Maxwell's demon is a device that gets information and trades it in for
thermodynamic advantage, in apparent (but not actual) contradiction to the
second law of thermodynamics. Quantum-mechanical versions of Maxwell's demon
exhibit features that classical versions do not: in particular, a device that
gets information about a quantum system disturbs it in the process. In
addition, the information produced by quantum measurement acts as an additional
source of thermodynamic inefficiency. This paper investigates the properties of
quantum-mechanical Maxwell's demons, and proposes experimentally realizable
models of such devices.Comment: 13 pages, Te
Improving the Efficiency of an Ideal Heat Engine: The Quantum Afterburner
By using a laser and maser in tandem, it is possible to obtain laser action
in the hot exhaust gases involved in heat engine operation. Such a "quantum
afterburner" involves the internal quantum states of working gas atoms or
molecules as well as the techniques of cavity quantum electrodynamics and is
therefore in the domain of quantum thermodynamics. As an example, it is shown
that Otto cycle engine performance can be improved beyond that of the "ideal"
Otto heat engine.Comment: 5 pages, 3 figure
The Effect of Focal Damage to the Right Medial Posterior Cerebellum on Word and Sentence Comprehension and Production
Functional imaging studies of neurologically intact adults have demonstrated that the
right posterior cerebellum is activated during verb generation, semantic processing,
sentence processing, and verbal fluency. Studies of patients with cerebellar damage
converge to show that the cerebellum supports sentence processing and verbal
fluency. However, to date there are no patient studies that investigated the specific
importance of the right posterior cerebellum in language processing, because: (i)
case studies presented patients with lesions affecting the anterior cerebellum (with or
without damage to the posterior cerebellum), and (ii) group studies combined patients
with lesions to different cerebellar regions, without specifically reporting the effects
of right posterior cerebellar damage. Here we investigated whether damage to the
right posterior cerebellum is critical for sentence processing and verbal fluency in four
patients with focal stroke damage to different parts of the right posterior cerebellum (all
involving Crus II, and lobules VII and VIII). We examined detailed lesion location by going
beyond common anatomical definitions of cerebellar anatomy (i.e., according to lobules
or vascular territory), and employed a recently proposed functional parcellation of the
cerebellum. All four patients experienced language difficulties that persisted for at least a
month after stroke but three performed in the normal range within a year. In contrast, one
patient with more damage to lobule IX than the other patients had profound long-lasting
impairments in the comprehension and repetition of sentences, and the production of
spoken sentences during picture description. Spoken and written word comprehension
and visual recognition memory were also impaired, however, verbal fluency was within
the normal range, together with object naming, visual perception and verbal shortterm
memory. This is the first study to show that focal damage to the right posterior
cerebellum leads to language difficulties after stroke; and that processing impairments
persisted in the case with most damage to lobule IX. We discuss these results in
relation to current theories of cerebellar contribution to language processing. Overall, our study highlights the need for longitudinal studies of language function in patients
with focal damage to different cerebellar regions, with functional imaging to understand
the mechanisms that support recovery
Performance of discrete heat engines and heat pumps in finite time
The performance in finite time of a discrete heat engine with internal
friction is analyzed. The working fluid of the engine is composed of an
ensemble of noninteracting two level systems. External work is applied by
changing the external field and thus the internal energy levels. The friction
induces a minimal cycle time. The power output of the engine is optimized with
respect to time allocation between the contact time with the hot and cold baths
as well as the adiabats. The engine's performance is also optimized with
respect to the external fields. By reversing the cycle of operation a heat pump
is constructed. The performance of the engine as a heat pump is also optimized.
By varying the time allocation between the adiabats and the contact time with
the reservoir a universal behavior can be identified. The optimal performance
of the engine when the cold bath is approaching absolute zero is studied. It is
found that the optimal cooling rate converges linearly to zero when the
temperature approaches absolute zero.Comment: 45 pages LaTeX, 25 eps figure
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